Step #1: Open the notification screen by swiping your finger from top to bottom.
Step #2: Tap the screen recording button from here.
If you can't see the screen recording button, you can add it with the edit button.
Step #3: Tap the Start button.
The countdown will start, and the screen recording will start as soon as it ends.
Step #4: Reopen the notification screen to stop recording.
Step #5: The screen recording will stop as soon as you tap the screen recording button again.
You can access the screen recording you have taken from your gallery or via Google Photos.