Gears Of War 5 is absolutely better with cross platform ! On my base Xbox one the visuals amazing. But I'm fortunate enough to be playing Ryzen 3900x and 5700 xt, the FPS does make a difference. I suck at this game so with pc a get little of advantage with FPS. Ultra setting you are in for a graphical experience that is a rare occurrence on console.
So far I'm enjoying playing online. I have not notice any lag. Xbox PC beta pass looks promising for PC gaming.