How to use the larger text in iOS 10/11 for iPhone/iPad/iPod Touch

1. Open the ‘Accessibility Settings’: Settings > General > Accessibility. (See the article Open Accessibility Preferences on this website for more information.)
2. Under the ‘Vision’ section, tap on ‘Larger Text’. Fig 1.
   
   Fig 1
3. To access the full range of text size options, tap on the toggle switch to the right of ‘Larger Accessibility Sizes’. Fig 2.
   
   Fig 2
4. To change the text size, drag the slider to the left or to the right. Fig 3.
   
   Fig 3
5. Enabling ‘Larger Text’ will not increase the size of the ‘title bar’ text but in iOS 11 if you long-press on the title bar the text will appear in the larger size in the centre of the screen (see Fig 5, below).Note: To enable this feature, you need to use ‘Larger Accessibility Sizes’ and set the text size above the 50% mark (see Fig 4).
   
   Fig 4
   
   
   Fig 5
6. When you are happy with your settings, either tap ‘Back’ in the top left of the screen to return to the main ‘Accessibility’ settings screen or press your device’s ‘Home’ button to return to the home screen.

More information:

In iOS11 it is now possible to add a shortcut for ‘Larger text’ settings to the ‘Control Centre’. See the article: Control Centre – iPhone/iPad/iPod Touch iOS 11 on this website.