iphone xs max ribbon cable

While you can take it to Apple to service it they may refuse to work on it since you opened it tried to install a screen yourself. You are probably going to need to find a reputable 3rd party shop that can do board level soldering and have them repair it for you. Your only other option is to so an internet search to see if there is a 3rd party site that sells the cable, or salvaged parts that would sell to you.

Apple does not recommend consumers fixing their own products. You should try taking it to an Apple Authorised Service Provider. Start here: Get Support.

Nope.

There are no user serviceable parts inside any iPhone.

Apple does not sell parts for any iPhone.

If you have to ask that question you need to take it to a 3rd party shop.