Quick Answer
Yes, with enormous headroom. The RTX 5090 runs Forza Horizon 5 at 1080p above 250 fps on the Extreme preset, far beyond what any 1080p panel can show. At this resolution the card is heavily under-used, so a 240Hz panel or a step up to 1440p or 4K makes more sense.
Forza Horizon 5 is exceptionally well optimised
Playground Games' engine is one of the cleanest in racing, so at 1080p the 5090 produces 250-320 fps on the Extreme preset with no instability. The benchmark tool will report very high averages, but a 1080p screen caps what you actually see. Leave settings maxed because the card has nothing better to do at this resolution; the Mexico map stays buttery during photo-mode and fast cross-country runs alike.
Better spent at 1440p ultrawide or 4K
Forza Horizon 5 is a showcase game, so the 5090's value appears at higher resolutions. At 4K Extreme it still clears 130 fps, and a 1440p ultrawide gives a wonderful sense of speed while staying above 200 fps. Pair the card with a Ryzen 7 9800X3D and consider a 1440p 240Hz or 4K 144Hz panel from Evetech, which range from roughly R9,000 to R30,000.
FAQ
What FPS does the 5090 get in Forza Horizon 5 at 1080p?
250-320 fps on the Extreme preset, well past any 1080p monitor's refresh. The card is dramatically over-specified for this resolution in this game.
Should I run Extreme settings on a 5090?
Yes. Even at maxed settings the frame rate is far higher than a 1080p panel can display, so there is no reason to lower quality at this resolution.
Is 1080p the right resolution here?
No. Forza Horizon 5 looks far better at 1440p ultrawide or 4K, where the 5090's power produces a visibly richer image while still holding very high frame rates.
Show off the 5090 at higher resolution Forza Horizon 5 is a visual showcase; pair the card with a 1440p ultrawide or 4K panel from Evetech to actually see the difference over 1080p.