I think photo mode only works with the poses that come with it. E.g. if a character just sits on a bench and you enter photomode, it will be standing on the bench instead.
So I suspect that poses from mods will not work with PM either, though I didn't try it. You could always take a "normal" screenshot though. With the "native camera" mod you can view it from better angles.
With the "Emotes" mod you can let the characters assume a lot of poses from the game to take a screenshot.
https://www.nexusmods.com/baldursgate3/mods/4744