With USB-OTG (On-The-Go) you can connect devices like a keyboard, mouse or even storage devices like hard disks and USB sticks to the Oppo-Smartphone. In order for the other devices to be recognized, USB-OTG must be activated in the Additional Settings. After ten minutes of inactivity, USB-OTG will automatically deactivate itself again.

Android 10 (ColorOS 7.0)
Step 1:  Open the  Settings
Step 2:  Tap on  Additional Settings
Step 3:  Enable or Disable  OTG connection
  1. Open the Settings
  2. Tap on Additional Settings
  3. Enable or Disable OTG connection

Oppo Instructions