Just like Longlegs, I like the movies that inspired this movie more than this one. Thanks to the horror thread I saw the 1997 Japanese horror/thriller Cure.
For this movie here are what I think are it's biggest influences.
1. Brian De Palma's Body Double 1984
Much like Maxxxine the main character is an actor of a horror movie trapped in a murder mystery. Both movies also give you a look into the world of pornogrophy.
2. Dario Argento's Tenebre 1982...or his The Bird with the Crystal Plumage 1970
The killer's motives match most with Tenebre. One death scene is also heavily stylized like Argento's films in the 80s.
The killer in Maxxxine look was cread in The Bird with the Crystal Plumage. Everytime the detectives are on screen in Maxxxine the movie is more humorous much like The Bird with the Crystal Plumage.
You can also watch his other movies Deep Red 1975(highly recommend), and Opera 1987 if you want more straight razor killers in heavily stylized mysteries.
3. Paul Schrader's Hardcore 1979
If you watched Maxxxine the connection is obvious. In this movie you also get a look into LA's sex work industry.
4. Ken Russell's Crimes of Passion 1984... or watch Psycho
Psycho was an inspiration for obvious reasons but Anthony Perkin's character in Crimes of Passion would fit into the world of Maxxxine much more. The lead character is also a sex worker.
5. Robert Vincent O'Neil's Angel 1984 & Gary Sherman's Vice Squad 1982
These are the only two movies I haven't seen yet but by just watching the trailers I can see the inspiration. Ti West has mentioned Angel as one of the inspirations himself.
I'm watching the Steelers and it was half time...I got bored