There are some kind of AI or Photoshop right? I keep seeing cross over items we never actually saw and it's breaking my brain to think there's crossovers I don't know about

I don’t think that these are AI. The guy who makes these is a huge comic book fan and expert. He uses some kind of computer program to put all of these images together. He puts out a brand new cover every day.
There have been several crossovers of different companies in the past. Mostly Marvel and D.C. characters. They started doing it back in 1977 with Superman and Spider-Man being the first. Then they had The X-Men and The New Teen Titans with a one-shot comic in 1981. In 1996 Marvel and D.C released a several issue miniseries featuring some each company’s characters. Over the years there have also been a few crossovers with independent comics characters. Nothing like these imaginary crossovers though.

Ok I figured it was either AI doing a mashup or a program picking and choosing various transparent background images and such

That could be it. I’m not sure. He has a website where he posts all of these and interacts with fans. There’s also another series of these crossover covers. They’re using the old “Marvel Two-In-One” series with The Thing, from “The Fantastic Four” comics. They have some of those with him and a non-Marvel character. Usually a D.C. character or characters.

Also - this cover works so incredibly well because of the near identical art between the two titles

I agree. Sometimes a cover will showcase art from the same artist, even if it’s from two different companies and two different time periods. I think that the Conan part of this cover was drawn by John Buscema. The Warlord part was drawn by Mike Grell, the artist who originally created him. They go well together.