iphone 13 - locked out after 15 digit reset.. no backup-- no reset password option (72 hour use of previous passcode option)

Did you try the original pass code? In case it was an app passcode that you changed.

You may have fallen for a scam, or been mistaken about what you actually changed, but provided you didn't change your Apple Account password you will at least be able to recover the phone itself though data that is unsync'd or not backed up will be lost

https://support.apple.com/en-gb/118430?iphone-authentication-type=iphone-with-face-id

gbaya wrote:

at one point it made me reset the password I use to unlock the phone to a 15 digit code.

This is very odd. Perhaps you should describe in detail all the pertinent events and steps preceding this request. Also, if you can, please describe the exact method of delivery and wording of this request, along with your specific actions just before its arrival.

Apple has never asked for a 15 digit passcode as far as I know. It certainly sounds like you have been hacked, or being asked to supply something other than an iPhone passcode.

Again, if you describe all relevant events and actions, perhaps we can assist further.

I didnt even initiate the ios upgrade ... it happened randomly during the day

It was you need to change your passcode.. needs to be 15 characters (instead of the 4-6 digits I use to open the phone)