Currently, there's no way to list all fields set as 'required' in a Field Configuration. The only way to find these fields is by going through each page of the Field Configuration and using the browser's 'find' feature (ctrl/cmd+F) searching for the word "Required". The problem with that solution is when there are a lot of pages you have to go through in order to verify all fields.

Suggestion

1. Implement the possibility to list all required fields more easily.
2. Remove the pagination of Field Configurations so it's possible to search for all required fields on the same page.
3. Create the ability to reorder fields based on whether they're required or optional.

Workaround

1. Go to https://<your site name>.atlassian.net/rest/api/3/fieldconfiguration and identify the ID of the field configuration you wish to check
2. Go to https://<your site name>.atlassian.net/rest/api/3/fieldconfiguration/<field configuration id obtained in step 1>/fields
   You will see the following JSON which included whether or not the field is required in the given field configuration:

   {
     "maxResults": 50,
     "startAt": 0,
     "total": 191,
     "isLast": false,
     "values": [{
       "id": "customfield_10000",
       "description": "Includes development summary panel information used in JQL",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10001",
       "description": "",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10002",
       "description": "Stores the organizations that are associated with a Service Desk customer portal requests. This custom field is created programmatically and required by Service Desk.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10003",
       "description": "Contains users needed for approval. This custom field was created by Jira Service Desk.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10004",
       "description": "",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10005",
       "description": "",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10006",
       "description": "",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10007",
       "description": "Choose the reason for the change request",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10008",
       "description": "Enter when the change actually started.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10009",
       "description": "Enter when the change actually ended.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10010",
       "description": "Holds information about which Service Desk was used to create a ticket. This custom field is created programmatically and must not be modified.",
       "isHidden": false,
       "isRequired": false,
       "renderer": "text-renderer"
     }, {
       "id": "customfield_10011",
       "description": "Provide a short name to identify this epic.",
       "isHidden": false,
       "isRequired": false,
       "renderer": "text-renderer"
     }, {
       "id": "customfield_10012",
       "description": "Epic Status field for Jira Software use only.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10013",
       "description": "Epic Color field for Jira Software use only.",
       "isHidden": false,
       "isRequired": false,
       "renderer": "text-renderer"
     }, {
       "id": "customfield_10014",
       "description": "Choose an epic to assign this issue to.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10015",
       "description": "Allows the planned start date for a piece of work to be set.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10016",
       "description": "Measurement of complexity and/or size of a requirement.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10017",
       "description": "",
       "isHidden": false,
       "isRequired": false,
       "renderer": "text-renderer"
     }, {
       "id": "customfield_10018",
       "description": "",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10019",
       "description": "Global rank field for Jira Software use only.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10020",
       "description": "Jira Software sprint field",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10021",
       "description": "Allows to flag issues with impediments.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10022",
       "description": "The targeted start date. This custom field is created and required by Advanced Roadmaps for Jira.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10023",
       "description": "The targeted end date. This custom field is created and required by Advanced Roadmaps for Jira.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10024",
       "description": "",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10025",
       "description": "",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10026",
       "description": "Adding both UUID and Location fields to a project, will enable JIRA Mobile Connect for that project.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10027",
       "description": "Adding both UUID and Location fields to a project, will enable JIRA Mobile Connect for that project.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10030",
       "description": "",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10031",
       "description": "Stores the users that are participants in service project customer portal requests. This custom field is created programmatically and required by service project.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10032",
       "description": "Stores request feedback in service project requests. This custom field is created programmatically and required by service project.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10033",
       "description": "Stores request feedback date in service project requests. This custom field is created programmatically and required by service project.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10034",
       "description": "The language which a request was raised in.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10035",
       "description": "Link services from the service registry to an issue.",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "customfield_10036",
       "description": "First Custom Field Checkbox desc",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "assignee",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "attachment",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "comment",
       "isHidden": false,
       "isRequired": false,
       "renderer": "wiki-renderer"
     }, {
       "id": "components",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "description",
       "isHidden": false,
       "isRequired": false,
       "renderer": "wiki-renderer"
     }, {
       "id": "duedate",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "environment",
       "description": "For example operating system, software platform and/or hardware specifications (include as appropriate for the issue).",
       "isHidden": false,
       "isRequired": false,
       "renderer": "wiki-renderer"
     }, {
       "id": "fixVersions",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "issuelinks",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "issuerestriction",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "issuetype",
       "isHidden": false,
       "isRequired": true
     }, {
       "id": "labels",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "priority",
       "isHidden": false,
       "isRequired": false
     }, {
       "id": "reporter",
       "isHidden": false,
       "isRequired": true
     }, {
       "id": "resolution",
       "isHidden": false,
       "isRequired": false
     }]
   }