Was playing bf4 the other day and decided to ramp up res scaling to 200% and it was still totally playable on a 64 man server, above 60 FPS. I know bf4 is quite old now but still, we are talking 1440p, ultra settings with 200% scaling, i.e. effectively 5k rendering.
I think 4k is very doable on this card.
It definitely is, I routinely play BF4 and BF1 at 4k.
BF1 is pretty great because it has full controller support (including aim assist) so I can play it on the big screen