Check these possibilities:
● If an app or feature on your device is not working, not appearing, or is restricted (grayed out), a frequent reason is it may have been disabled using Screen Time, or by a technology administrator if you are using a device owned by an employer or educational institution.
- Read this support article If your Apple ID or other options are greyed out in Settings —> If your Apple Account is grayed out in Settings, or you can't sign out - Apple Support
Tap your Settings app > Screen Time > Content & Privacy Restrictions > scroll to Accounts > tap Allow Changes and turn on.
If the issue persists, also try going to Settings > Screen Time and turning off Share Across Devices
- If the device is managed (check: Settings > General > VPN (or Profiles & Device Management), contact the technology department of the organization that is doing the managing.
● Situation where a VPN was preventing action —> Unable to sign out of my Apple ID on my i… - Apple Community
To test for this, remove the VPN entirely, don’t just turn it off.
post by sberman at How do I update my iCloud account picture… - Apple Community
“Apple uses two distinct photos:
Your Apple Account photo. This is set at Settings > [your Apple Account] > Personal Information. You may change the photo at the top there.
Your Contacts photo. This is changed in the Contacts app at My Card. You may edit the card and change the photo there.”