As we get older, many of us find it becomes more and more difficult to read small print. Some people already use their iPhone as a magnifier by downloading a dedicated magnifying glass app from the App Store or by simply opening the Camera app and zooming in to see more detail. However, there is a built-in magnifier feature on the iPhone that is more convenient to use than these other options. It even includes a light and has the ability to adjust contrast and color.
Enable the Magnifier
Before you can use the magnifying glass feature, it has to be enabled by going to Settings -> Accessibility -> Magnifier and set the slider to the on position. You should also enable Auto-Brightness to help in low light conditions.
Next, scroll to the bottom of the Accessibility screen and select Accessibility Shortcut. Then select Magnifier from the list.
Using the Magnifier
To use the magnifier, quickly press the iPhone’s Side button three times if you have an iPhone X or later, or the Home button three times for earlier iPhone versions.
There are controls at the bottom of the window to zoom, turn on the flash as a light, adjust contrast and color, and lock the magnifier to your custom settings.
Add Magnifier to the Control Center
If you prefer to access features using the Control Center, the Magnifier can be added to the Control Center bu going to Settings -> Control Center and tapping Customize Controls. Scroll down to More Controls section and tap the add button 
next to Magnifier.
The Magnifier can then be opened directly from the Control Center.
