The best right now is probably the Nvdia RX3090 or Radeon RX 6900 XT - but the cheapest of those is more than x2 the cost of a XSX - just for the card.
EDIT - actually, here ya go, a Radeon RX 6800 (which costs around $579) can run Gears 5 at 4K at over 70fps:
