The night mode (night protection) can be manually switched on or off on the Oppo, or a schedule can be set where the night mode is automatically switched on and off at a specified time.

Android 10 | ColorOS 7.0
Step 1:  Open the  Settings
Step 2:  Tap on  Display & brightness
Step 3:  Tap on  Eye comfort
Step 4:  Enable or Disable  Schedule time
  1. Open the Settings
  2. Tap on Display & brightness
  3. Tap on Eye comfort
  4. Enable or Disable Schedule time

Oppo Instructions