Forgot my apple ID

To answer the question asked:

If you forgot your Apple ID - Apple Support

However, access to an iPad generally requires entry of a Passcode.

If that’s what you’ve actually forgotten, see this:

If you forgot your iPad passcode, use your Mac or PC to reset it - Apple Support

So the third possible course of action is:

https://iforgot.apple.com/

So now ALL alternatives for recovery of your device have been provided.

If further assist is needed:

Official Apple Support

Best of luck. 👋