Planning to buy a UHD monitor. Will 4K Games from PS4 Pro be downscaled to UHD? How will it look?

Hi

I'm a noob when it comes to consoles. I'm planning to buy this monitor. It supports UHD resolution.

For games like FIFA 17 etc, AFAIK, PS4 can run it in 4K. Will the game footage be downscaled to UHD. I assume it'll look better than 1080p.

Or 1080p game footage is upscaled to UHD. I assume it'll look bad.