One card can absolutely run 4 monitors.
Will it get you the framerates you want? Hard to say. Depends on which game and what settings you’ll use.

However using 2 cards to run a single game doesn’t realy work anymore, since SLI has been dropped.

Also GPUs don’t saturate PCIE 16x bandwidth anymore. Even a 5090 might only lose low single digit performance at 8x. If you could run 2 cards, that would easily be better with each at 8x, than one at 16x.