If you have forgotten the ScreenTime passcode, one of the two procedures outlined within this link should resolve the problem:
If you forgot your Screen Time passcode - Apple Support
If your iPad is capable of supporting iPadOS 13.x, you should update to the most current version before attempting to resolve a forgotten ScreenTime passcode. The most recent iPadOS updates have introduced a new mechanism whereby a forgotten ScreenTime passcode can be reset without wiping the iPad.
To reset a forgotten ScreenTime passcode on older versions of iOS/iPadOS, the iPad must be reset “as new”, losing all locally stored data. In this situation, you’ll not be able to restore your data from an iCloud or iTunes backup - as the forgotten passcode is integral to the backup.
Restore your iPhone, iPad, or iPod to factory settings - Apple Support
You will need access to either a Windows PC (with iTunes for Windows installed - or the more recent Apple Devices App) or a Mac (with iTunes or Finder - as appropriate for the installed version of MacOS). Ensure that your installed version of iTunes has been updated to the most recent version; the essential device drivers are included.
Download and use iTunes for Windows – Apple Support
Update to the latest version of iTunes – Apple Support
Apple Devices App (Windows PC):
https://apps.microsoft.com/detail/9np83lwlpz9k?hl=en-ms&gl=MS
(*) If you don’t have access to a suitable computer of your own, that of a helpful friend or family member will suffice. Alternatively, the technicians at the Genius Bar of your local Apple Store or Apple Authorised Service Provider (AASP) will be delighted to assist.
Genius Bar Reservation and Apple Support Options - Apple
