Who can create or edit rules for someone else?
Jira admins and Out of Office Admins can, for anyone, including rules people wrote for themselves; Space Admins can, for members of the spaces selected for them, and that role needs both a grant in the app and space administration in Jira.
Grants are made under App Settings > Permissions, where Out of Office Admin takes users or groups and Space Admin is granted to spaces.
Open the person from Team Availability > Show details and use Add rule for this user.
Related pages
Permissions and Access Requirements - where this is covered in full.
User Permissions - more questions on this topic.
