Game resolution and size of sprites?

I make a platform game (which uses camera) that is primarily supposed to be played on the phone. I create all the graphics as a vector and export as PNG so I can basically choose any size.

What resolution should I have in the “resolution and rendering” in gdevelop properties?
Any tips on size (in PX) on my sprites so that they do not feel too big or tiny, are there any guidelines? Ex size platforms and player, width and height?

See this video maybe it will help you