Currently, the default "Owner" field is not available for Themes in Jira Align UI. Adding a Custom field as "Owner" is the only option; however, the “user-picker” type of custom field is not supported. Hence, the admin/user will need to type in the email address manually.

It is not possible to add the "Owner" field to the Theme via API. The owner team is read-only, and actually, it is the creator instead of the owner of the Theme.

This enhancement request is raised to add the default "Owner" field to Themes.

Regards