Sounds cool. Probably you don’t need to dive into technicals very far then - what a relief for you :).
Yeah, it can be hard to have a sense of scale until we have some details in the scene. That is why using something common like the mannequin can be so helpful. In fact, if you are just working on artistic scenes, probably you dont necessarily need to even look at any numbers at all, just use a mannequin for human sized reference and base everything aesthetically from that.