If you have forgotten your Screen Time (a.k.a. Restrictions) passcode, this help page will explain the available processes to either remove or (for iOS/iPadOS 13.4 or later) reset the passcode:
https://support.apple.com/en-us/HT211021
You should note that, if Restoring your device from an iCloud or iTunes backup, the Restrictions Passcode that you have forgotten will be restored along with your data. As such, if your devices can support iOS/iPadOS 13.4, it would be in your best interest to update to this version before attempting to resolve issues with the Restrictions Passcode.
If you device cannot support iPadOS 13.x, you will have no alternative other than to set-up again as new. In this situation, you should endeavour to copy as much of your information to Cloud Storage before attempting the Restore process - as all locally storage data will be lost.
I hope you find this information to be helpful in outlining your two potential recovery methods.