Launch the Settings app on your touchscreen Apple device. Tap General. Tap Accessibility and scroll to the Vision section. Tap Zoom. Turn the Zoom function on by swiping the circular switch to the right. If you wish to turn the function off again, simply return to this screen and swipe the switch to the “Off” position. [1] X Research source
Repeated double-taps on a picture may zoom in until a set point, and then begin to zoom back out. Double-taps may also just zoom in, then stop zooming when a threshold is reached. A double-tap will fit text to screen, in order to allow an optimal reading comfort.