We can add more user accounts on the OnePlus smartphone to create a separate area for each user, which provides personal use for apps and other settings.

Note: Some device settings affect all user accounts, such as connecting to a wireless network.
The device administrator can delete all user accounts without restriction.

Android 10 | OxygenOS 10.0
Add user account -  Open the  Settings
Add user account -  Tap on  System
Add user account -  Tap on  Multiple users
Add user account -  Tap on  Add user
Add user account -  Confirm with  OK
  1. Open the Settings
  2. Tap on System
  3. Tap on Multiple users
  4. Tap on Add user
  5. Confirm with OK

OnePlus Instructions