Themes : Setting Default Properties: How do they work in Makie?

I’ve just begun diving deeper into Makie. How do themes work?
What attributes need you to call a parent Struct and what attributes can you call without a struct? I can’t set a default Scene camera for instance.

I can say

custom_theme = Theme(
    size=(600, 400),
    backgroundcolor=:black,
    ) 
set_theme!(custom_theme)
s = Scene()

and it’ll work fine.

but adding

camera=cam2d!

or

Scene = (camera = cam2d!,)

Seems to not work. How do I set the camera to what I like by default?

Scatter = (markerspace=:data,)

was something that worked for me.

What is it that works and does not work?

Any kind of niche Parent Structures involved? I’m a little newbie so don’t know what’s going on.