Is it possible another person is controlling all my devices?

Generally, no.

If your device was issued by a company or organization, it may have a configuration profile on it for moderation reasons. To see if your device has a configuration profile, go to Settings > General > Profiles & Device Management. If you don't see the 'Profiles & Device Management' option, your device is not controlled by MDM.

Perhaps you could respond with some more information about what you're experiencing?

Ah, MDM, good question! :)👍

No.

What is happening that makes you ask this question in the first place?

Thanks!