USB debugging is a feature that allows developers (programs) to have advanced access to the Oppo smartphone, but to enable USB debugging, the developer options must first be enabled.

Android 10 | ColorOS 7.0
Step 1:  Open the  Settings
Step 2:  Tap on  Additional settings
Step 3:  Tap on  Developer options
Step 4:  Enable or Disable  USB debugging
Step 5:  Confirm with  OK
  1. Open the Settings
  2. Tap on Additional settings
  3. Tap on Developer options
  4. Enable or Disable USB debugging
  5. Confirm with OK

Oppo Instructions