'iPhone Unavailable' after multiple failed password attempts on iPhone 15

See what to do here:

If you’ve forgotten your iPhone passcode or your iPhone is disabled – Apple Support (AU)

Note this process will completely erase the iPhone; you’ll need your AppleID credentials to be able to restore from a backup.

The phone will need to be wiped, but the data can be restored as long as you have a backup.

If you see a iPhone, iPad, or Apple Vision Pro unavailable message or Security Lockout screen - Apple Support

If you are unable to use that method, then you will need a computer to reset the Passcode.

If you forgot your iPhone passcode or your iPhone is disabled - Apple Support

You need to plug the iPhone into iTunes on a computer. If you have a recent backup you can updated it to the recent backup if not try updateding the iPhone to the latest version on iTunes if that dosent work you might need to factory reset the iPhone