I can’t open iPhone forgot password

You were looking at this article........If you forgot your Apple ID password ........and it is one way to erase / reset your phone so you can set it up again.

If you want to try to erase / reset the phone without using a computer.......you can use this Apple Support document......If you see an iPhone or iPad unavailable message or Security Lockout screen - Apple Support

Once the phone has been reset, you can restore the phone using your current backup, so the phone will look just like it did before you forgot the passcode.

For the future.....it might be a good idea to write the new passcode down and keep it in a safe place.....even if you think that you will never forget it.