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?

No.

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

Ah, MDM, good question! :)👍

Thanks!