It doesn't depend that much on KORD, it depends of how much other stuff you have and how high your settings are. In general, you'll want to have a fast video card with lots of VRAM.
We used both the standard nVidia 1070-1080 with 8GB and the 1080 Ti during most of the development, and lately we tested on 2070, 2080 and 2080 Ti. My laptop has a 1080 mobile with 8GB, and runs KORD just fine.
As indicated in the manual and in the KORD V2 web page and on the purchasing page too, the minimum recommended amount of VRAM to use the scenery in its full resolution ( some textures are 4K, most are 2K, some are 1024x1024 ), is 8GB.