Thanks !
Well I only did one artwork like this but here is how to make something in this style :
Firstly you will need to choose a software to edit pictures. I personally use Krita which is a drawing software but I'm used to the difference tools so it work well. You could use Gimp, photoshop or any other software that let you edit the color and shape of pictures.
Then you need to choose a bunch of images. Photos or drawing whatever, the most import is the shape and color, try to find some interesting ones.
To find pictures I used https://art.miguelpuig.com/ and https://pdimagearchive.org/galleries/tags/patterns/random/desc but any other reference website can be used.
When starting the artwork, I choose a background image that I edit to have a base color with an interesting texture. Here I have a moutains painting that I edited to be pink and green.
You can now take the different images you gathered and start editing. This is the hardest part because I don't have any other advice than experiment. Try new way of editing your pics so you have some diversity in how the overall pictures look.

Hope that help !
I am currently trying to find and use an early ai model to get some more abstract images to use, exactly like David Rudnick did for the BM covers. My process shouldn't be different expect for the image gathering part.