Depending on the file being played, we can set the Xiaomi smartphone to display subtitles/Captions when they are available,
adjust the style, whether the text is displayed on a dark background, and set the text size. In addition, the Xiaomi device offers the ability to create a custom style in which we can specify a font, change the background transparency, or select a border.

Note: in this tutorial we will create a personalized style, choose the font family "Italic" and set the text transparency. the steps mentioned above are only for illustration and can be skipped. other options can be reached the same way.

Android 10 (MIUI 12.0)
Step 1:  Open the  Settings
Step 2:  Tap on  Additional settings
Step 3:  Tap on  Accessibility
Step 4:  Tap on  Hearing
Step 5:  Tap on  Caption preferences
Step 6:  Enable or disable  Accessibility
  1. Open the Settings
  2. Tap on Additional settings
  3. Tap on Accessibility
  4. Tap on Hearing
  5. Tap on Caption preferences
  6. Enable or disable Accessibility

Xiaomi Instructions