How to Stop the iPhone from Magnifying Your Wallpaper Photos

Turn off paralax by going to Settings → General → Accessibility → Reduce Motion.
Now go back to Settings → Wallpaper & Brightness.Choose Wallpaper, tap whichever screen you’d like to modify. Pick your photo.

You’ll notice that whatever image you choose will be less magnified. Not perfectly zoomed out, but definitely an improvement. 

That’s about it! Hope I helped.For more information visit yahoo tech!