There seems to be a large amount of people who bought the Apple iPhone or iPad who have problems with the unit magnifying the screen 2X and making the graphics huge to a point where the screen is too big to be usable.
Apparently this is a feature with the iOS operating system. What has most likely happened is you may have accidentally enabled the zoom feature by double tapping it with 3 fingers.
To fix this issue, simply double-tap on the screen again with 3 fingers and the screen will go back to normal and eliminate the magnification.
If you want to disable this feature and prevent this problem from happening again, you can go to “Settings” > “General” > “Accessibility” and turn off “Zoom“.