A:Answer So only games that say they were developed for series X|S will ever see 120fps and they have the Series X|S on the game case or in the description when you download them. Older games are not going to run at 120fps. This also has a lot to do with what you have the Xbox connected to the TV/monitor has to be capable of the resolution hz and fps you are wanting. But honestly if high performance and fps means that much to you save more money and buy the series X because the series S is probably going to disappoint you because it is not going to hit 120fps as often has the series X will and is not going to run as fast or smooth as the series X there is a reason why the series X is out there and cost $200+ more than the series S. I am sure the folks at Microsoft made it so the xbox would drop fps before it let you experience a bad image, game lag, pixelated cut scene, game crash, and etc...
