Open the Settings app
Tap Display & Brightness
Tap Text Size
Drag the slider to the right
For even larger text, go back to Settings
Tap Accessibility
Tap Display & Text Size
Tap Larger Text
Turn on Larger Accessibility Sizes
Drag the slider to the right
To make everything on the screen bigger, go to Settings
Tap Display & Brightness
Tap Display Zoom
Select Larger Text
Tap Set
Restart if prompted