Microsoft published an article yesterday which spoke more of backward compatibility on the Series X and Series S. There was one paragraph in the article that illustrates how hard it is to pin anything down on how a lot of games will be affected... there's a range of benefits from none, to resolution changing and frame rate doubling. Read this and see how you think PGA TOUR 2K21 might be affected by it:
Backward compatible games run natively on the Xbox Series X and S, running with the full power of the CPU, GPU and SSD. No boost mode, no downclocking, the full power of the consoles for each and every backward compatible game. This means that all titles run at the peak performance that they were originally designed for, with significantly higher performance than their original launch platform, resulting in higher and more steady framerates and rendering at their maximum resolution and visual quality. Backward compatible titles also benefit from significant reductions in load times due to the massive leap in performance from our custom NVME SSD at the heart of the Xbox Velocity Architecture.
The highlighted sentence seems to suggest that it could be anything from indistinguishable from the XBox One version, to higher and steadier frame rates, along with maximum resolution and visual quality. The question is, how much of that could be done without any developer intervention? I don't know.
There are three take aways that I can hang my hat on from what I've read so far about backward compatibility:
1.) The load times will be four to five times faster than the XBox One X version.
2.) All games will get benefit from the automatic application of 16X anisotropic filtering (we already have that on the XBox One X, btw).
3.) Each game will get automatic HDR support.
I've seen nothing in print that says that 2K21 is running at a locked 30 FPS in 4K, but we did get such an admission about TGC 2019. 2K21 appears to be running at a 30 FPS lock. What I'm not sure of is how that lock is imposed. Is it by a means that the Series X can't supersede and seek or establish its own frame rate? This gets into an area that requires some esoteric knowledge that's above my pay grade.