Being able to hide (or show) the contact photos in iMessages in iOS requires iOS 9 or later on the device:
- Leave Messages app in iOS if you haven't done so yet.
- Open the Settings app and go to “Messages”
- Locate the switch for “Show Contact Photos” and turn that to the OFF position.
How do I make my contact pictures bigger on iPhone?
Find and select the contact you want to update to a fullscreen caller ID. Press the edit button in the top right of the contact card. Tap the edit button under the contacts profile image (top left of the screen) Select Choose Photo and select the appropriate image from your photo library.