The notification tone can not only be changed in general, but also individually for each app by adjusting the ringtone settings via the app management.

Android 10 | ColorOS 7.0
Step 1:  Open the  Settings
Step 2:  Tap on  App management
Step 3:  Tap on  App list
Step 4:  Tap on  App  you want
Step 5:  Tap on  Manage notifications
Step 6:  Choose desired  Notification category
Step 7:  Tap on  Ringtone
Step 8:  Choose desired  Notification sound
  1. Open the Settings
  2. Tap on App management
  3. Tap on App list
  4. Tap on App you want
  5. Tap on Manage notifications
  6. Choose desired Notification category
  7. Tap on Ringtone
  8. Choose desired Notification sound

Oppo Instructions