We can mute an incoming call by flipping the OnePlus smartphone, disabling the ring tone and vibration of the notification.

The feature must first be enabled in the phone app's advanced settings, which can be done at any time.

Android 10 | OxygenOS 10.0
Step 1:  Open the  Phone app
Step 2:  Open the  menu
Step 3:  Open the  Settings
Step 4:  Tap on  Advanced
Step 5:  Enable or disable  Flip To Silence
  1. Open the Phone app
  2. Open the menu
  3. Open the Settings
  4. Tap on Advanced
  5. Enable or disable Flip To Silence

OnePlus Instructions