Banner notifications are displayed at the top of the screen for a few seconds, and for incoming calls they are displayed for the duration of the ringing.

Banner notifications can be enabled or disabled individually for each app, even for individual categories.

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:  Enable or Disable  Banners
  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. Enable or Disable Banners

Oppo Instructions