Open Settings
Tap Control Center
Tap the Add button next to Screen Recording if it is not already included
Open Control Center
On iPhone with Face ID, swipe down from the top-right corner
On iPhone with a Home button, swipe up from the bottom edge
Tap the Screen Recording button
Wait for the three-second countdown
To record audio, press and hold the Screen Recording button, then tap Microphone On
To stop recording, tap the red status bar or red recording indicator
Tap Stop
Find the recording in the Photos app