Lockscreen password
I forgot my lockscreen password. What should I do?
iPhone 6 Plus, iOS 12
Question marked as
If you forgot your iPhone's passcode, you will have to restore the phone in order to regain access to it. Note that you will need a Mac or PC to perform the restore process. Also note that this process will completely erase the phone. The only means to restore any data on the phone would be from a backup.
Ref: If you forgot your iPhone passcode - Apple Support