We can specify when the OnePlus smartphone's screen should automatically turn off and go into sleep mode.
As the display is one of the biggest consumers of power, it is recommended not to set the time until automatic standby too long.

If a display lock has been set up using a pattern, PIN or password, the device is also locked immediately.

We have the choice between the following timers or periods of inactivity until the lock or sleep mode takes effect:

Android 10 | OxygenOS 10.0
Step 1:  Open the  Settings
Step 2:  Tap on  Display
Step 3:  Tap on  Sleep
Step 4:  Set the  duration until sleep
  1. Open the Settings
  2. Tap on Display
  3. Tap on Sleep
  4. Set the duration until sleep

OnePlus Instructions