Unlock my iPhone passcode

You cannot unlock your Passcode using your iPad. Your only option is to erase the device and your can use your Apple ID to do this without a computer if using iOS 15.2 or greater by following this support article:

If you see an iPhone or iPad unavailable message or Security Lockout screen - Apple Support

If that is not possible, you will need to use a computer by doing this:

If you forgot your iPhone passcode - Apple Support

You can't use an iPad to unlock your iPhone. You will need to use a computer for this purpose.

Ref: If you forgot your iPhone passcode - Apple Support