iphone 15 Pro Max correct passcode is not working after update

There is no "forget passcode" option on iPhone. If your passcode isn't working, your iPhone is displaying a message that it is unavailable for a period of time or if enough attempts to enter a passcode which the phone doesn't believe is correct, it becomes disabled.

In either situation, the phone needs to be erased and set up again from your most recent backup. Here are the two links which you'll choose from depending on your current status:

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

If you forgot your iPhone passcode - Apple Support

Make sure you are using the most current version of iTunes on your computer. And follow the directions EXACTLY as written. It can take a few tries to get it to work.