We can activate a key shortcut on the Xiaomi smartphone to get quick access to a function, such as TalkBack or color correction. To do this, we press both volume buttons for three seconds. We can determine whether this function is already allowed on the lock screen.

Note: In this guide we will enable the volume key shortcut, select a function and give permission to be available from the lock screen. The mentioned steps are for illustrative purposes only and can be skipped.

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  Volume key shortcut
Step 5:  Enable or disable  Accessibility
Step 6:  Tap on  Shortcut service
Step 7:  Choose a  Shortcut service
Step 8:  Tap on  Allow 
Step 9:  Tap on  Back
Step 10:  Enable or disable  Allow from lock screen
  1. Open the Settings
  2. Tap on Additional settings
  3. Tap on Accessibility
  4. Tap on Volume key shortcut
  5. Enable or disable Accessibility
  6. Tap on Shortcut service
  7. Choose a Shortcut service
  8. Tap on Allow 
  9. Tap on Back
  10. Enable or disable Allow from lock screen

Xiaomi Instructions