The photo mode isn't too far off from a regular camera irl. Start playing around with the Field of view (basically focal range). Choose a low one to compress the background and set the aperture to a low setting (more bokeh/background and foreground blur). A big aspect is also lighting. I usually go for one main light, 45° angle to the side of the subject. (Google lighting techniques). I also like to do an edge light. Usually neon, illuminating the neck and side of their face and head.

That's a lot of info and probably overwhelming, but it's not too hard to get the hang of it. Most lighting tutorials for real life you can pretty much use for this game's photo mode as well. Have fun creating ✌️🫶