Hi natsc,
welcome to the Apple (user-to-user) Community.
They were good things to try!
If you haven't already done so, you might want to try updating to the latest iOS 16.3.1
Otherwise:
For Camera: Take Live Photos with your iPhone camera – Apple Support
Says:
To play the Live Photo, tap the photo thumbnail at the bottom of the screen, then touch and hold the screen to play it.
and
Note: "Live Photos aren’t available when ProRAW is turned on."
_______________________________________________________
For Photos app:
View photos in the Photos app on iPhone – Apple Support
says:
For individual photos:
Tip: When viewing a Live Photo
, touch and hold the photo to play it."
Play videos and slideshows in the Photos app on iPhone – Apple Support
says:
"You can also create slideshows of the photos, videos, and Live Photos in your library".
Else: Seems to be nothing there about Autoplay.
If you wish you could contact Photos Support,
Photos Support Website
Photos - Official Apple Support
All the best :-)