I've been using Midjourney and Photoshop to create a style & cultures for my fictional universe (featured in a video game I'm creating).
Here's some concept art of character classes.
For context: the setting is 500 years after monsters destroyed the world. Humankind is endangered, and technology has regressed to the point where even guns are incredibly rare. The world has been warped by something that nobody quite understands, and new strange - almost fantastical - biomes have taken shape. It's what you'd get if you crossed The Last of Us with Final Fantasy.
Edit: you can follow the project here at https://www.facebook.com/WorldOfWintersteel