This issue was closed because most date / time formats in Jira Cloud issues are already set per user depending on the Language they select on https://id.atlassian.com/manage-profile/account-preferences
This is documented here: How do date and time formats work in the issue view?
There are some fields that still don't change format depending on one's language setting. We have created separate feature requests for this e.g. JRACLOUD-81778 The "Added date" format in the Attachments section on issue view should respect the user's language settings
Request for JIRA to allow per-user customization for date / time format. Currently it only allows changing a global date / time format by administrator.