This problem is the common problem across iPhone users, as enlarged images or icon on the iPhone make it difficult or people to see or to navigate. This may be caused due to accessibility feature or zoom and it easy to fix most of the time.
On your iPhone where the problem is being found, hold three figures together and double tap the screen. It would automatically recover to normal.
Also you can go to Settings – General  – Accessibility and turn it zoom off.
Hope this would help.
