Use Face ID ( > Face ID & Passcode, then turn on options below Use Face ID For.
You can temporarily prevent Face ID from unlocking your iPad.
Press and hold the top button and either volume button for 2 seconds.
After the sliders appear, press the top button to immediately lock iPad.
iPad locks automatically if you don’t touch the screen for a minute or so.
The next time you unlock iPad with your passcode, Face ID is enabled again.
Go to Settings Change when iPad automatically locksTurn on Lock Screen features on iPad