I doubt it's her. It says she has already been everywhere but also will be everywhere in the next year or so which doesn't make sense. McKenna's parents weren't Hollywood people, so that backstory wouldn't make sense. Also McKenna has been fairly notoriously boyfriend averse in public, which make that whole "whomever she is with" thing not match.
It's not Odessa because she's 25 and they say they're a teenager still.
Butters has already been in her most high profile movie, and not a ton else so this wouldn't make a whole lot of sense for her.
If you remove the "A-List" part from the equation, I'd guess Alyvia Alyn Lind since her mother is known for being... open, and her sisters have been with some extremely skeezy dudes.