I don't think I was clear in my post, I mean its going to be impossible to cram all the detail you want into a poker sized workspace
Yes - which is why I mentioned that NO ONE designs and creates a card the exact finished card size - unless you have a lot of 'one-hair brushes' lying around; almost everything is produced at a larger scale and reduced down. If you were to take an image of the Sistine Chapel Ceiling and scale it down to the back of a playing card there would be too much detail that would be lost.
When I had to re-scale my b/w drawings I was mostly adding height, so I was mostly moving image elements up or down; if someone was looking at something that was moved up, you have to adjust their gaze to look 'up'. Cramming a lot of details in makes you ask which details are the most important and what size they need to be. In the limited space of a Tarot card it might be better to have fewer but well-detailed images than a card full of a lot of stuff like a table at a flea market where too many things are vying for your attention at once.