The OnePlus smartphone automatically notifies us when a system update is released.

In case a notice about an available update has been missed or deleted, we can manually check the availability of software updates at any time.

Android 10 | OxygenOS 10.0
Step 1:  Open the  Settings
Step 2:  Tap on  System
Step 3:  Tap on  System updates
  1. Open the Settings
  2. Tap on System
  3. Tap on System updates

OnePlus Instructions