Depends on how mature/finalized is my idea.
If I have a very clear idea on what I want to do, I either go through my photo stock (landscape, museum objects, etc) or image search engine. I do a rough draft and then adapt for light/shadow and for the style I want. For pose, it’s very hard to get exactly what I want from ref pic, so I adapt for angle.
If I don’t have anything really clear already plan and just a rough feeling/mood/scene I might just do image search and shamelessly copy the pose (same light source, angle) only using my own style, and then adapt panel background and storytelling to match it.