By default, the Oppo smartphone automatically obtains the date and time over the network, but you can enable or disable this function in the Additional settings.

Android 10 | ColorOS 7.0
Step 1:  Open the  Settings
Step 2:  Tap on  Additional settings
Step 3:  Tap on  Date & time
Step 4:  Enable  Network-provided time
  1. Open the Settings
  2. Tap on Additional settings
  3. Tap on Date & time
  4. Enable Network-provided time

Oppo Instructions