We can change the font size of text displayed on the OnePlus smartphone's screen to make it easier to read.

If an app does not have its own settings for the displayed font or font size, we can set the font size as follows:

Android 10 | OxygenOS 10.0
Step 1:  Open the  Settings
Step 2:  Tap on  Display
Step 3:  Tap on  Font size
Step 4:  Swipe  left  or  right  to adjust the  Font size
  1. Open the Settings
  2. Tap on Display
  3. Tap on Font size
  4. Swipe left or right to adjust the Font size

OnePlus Instructions