How to add height to a room using paint?

[Michigan T]

We are renovating a small cottage. Two of the bedrooms are on the back, and have tongue-and-groove (unifnished) on the walls and ceiling. The rooms are small, and the ceiling slants.
The floors will be carpeted.

I would like to know how to add height to the rooms using paint. Would you paint the ceiling white and leave the walls wood, or paint the walls white and leave the ceiling wood-tone? I think the wood-tone ceiling and white walls would be my preference. Looking for opinions!!