When a new notification arrives on the Oppo smartphone, the notification tone sounds. This is usually the case with all apps except the phone and message app. The notification tone can be changed in the sound settings of the Oppo device.

Note: You can also use your own notification tone.

Android 10 | ColorOS 7.0
Step 1:  Open the  Settings
Step 2:  Tap on  Sound & vibration
Step 3:  Tap on  Default notification sound
Step 4:  Choose desired  notification sound
  1. Open the Settings
  2. Tap on Sound & vibration
  3. Tap on Default notification sound
  4. Choose desired notification sound

Oppo Instructions