Does 2D sprite (art asset) size matters ?

Hello, I'm making art assets for a 2D game, since game is quite small I would like to produce really high resolution and detail background and player model, I usually work with images up to 10000x6000 while drawing.

• Should I scale assets down before importing to lets say 4096x2160 ?

Or

• Should I scale them down inside unity to fit camera ?

Or

• Should I increase camera's size to cover needed area ?

Which method is most acceptable and is there difference when I increase camera's size or scale down whole scene ?

*game is for PC to be played on 1920x1080