Much of your iPad’s advanced functionality simply won’t work if you disable/remove the device Passcode such as TouchID/FaceID and stored account Passwords (Keychain).
As documented by Apple in its Security Guide, for devices with TouchID or FaceID enabled, you device Passcode is reportedly required in the following circumstances…
A passcode or password is also required if the device is in any of the following states:
• The device has just been turned on or restarted
• The user has logged out of their Mac account (or hasn’t yet logged in).
• The user hasn’t unlocked their device for more than 48 hours.
• The user hasn’t used their passcode or password to unlock their device for 156 hours (six and a half days), and the user hasn’t used a biometric to unlock their device in
4 hours.
• The device has received a remote lock command
• The user exited power off / Emergency SOS by pressing and holding either volume button and the Sleep/Wake button simultaneously for 2 seconds and then pressing Cancel.
• There were five unsuccessful biometric match attempts (though for usability, the device might offer entering a passcode or password instead of using biometrics after a smaller number of failures).
When Face ID with a mask is enabled on an iPhone, it’s available for the next 6.5 hours after one of the following user actions:
• Successful Face ID match attempt (with or without a mask)
• Device passcode validation
• Device unlock with Apple Watch
Any of these actions extends the period by an additional 6.5 hours when performed.
While not necessarily recommended, instead of fully disabling the device Passcode (and with it significant functionality of your iPad), consider simply disabling your iPad's Auto Lock setting. With this disabled, your iPad will remain unlocked unless it is manually locked, or the iPad is shut-down and restarted:
Settings > Display & Brightness > Auto-Lock - set to Never
If you remain determined to fully disable the device Passcode - and accept that you will lose functionality in so doing:
Settings > TouchID | FaceID & Passcode > Turn Passcode Off