The Xbox Series S is, on paper, every bit as feature-rich as the Series X. It's based on the same fundamental RAM, storage, CPU, and GPU technologies - which of course means that it is ray tracing capable. You can absolutely get RT acceleration on the system, just like any other RDNA 2-based hardware platform. In practice, it's a bit more complicated. The Series S has a modest 4TF GPU paired with a meagre 10GB of RAM, which makes it challenging to implement complex ray-tracing effects on the console. Most recent games lack ray-tracing on Series S, even if they pack one or more effects on Series X and PS5.
Series S ray-tracing games are so scarce, even two years in, that you can almost count meaningful implementations on two hands. By my count there are just 15 titles in total that use hardware or software ray tracing techniques on the platform, though perhaps there are some low-profile titles we've missed (and maybe there's a case for Gears 5-style screen-space-based global illumination). While the diversity of RT titles might not be there, that's not to say that there isn't software on Series S where ray tracing isn't key to the experience - and by reckoning, there are three experiences where the technology is present and correct on the junior Xbox and works beautifully.
Metro Exodus Enhanced Edition is the standout example. The per-pixel RTGI is very high quality, realistically shading scenes and ensuring that everything looks grounded and correct within the game world. There's a consistency to the lighting that really impresses here, and is a cut above most titles that rely on precalculated solutions. Dynamic objects like characters particularly impress, with rich and grounded lighting. Stacked up against its last-gen predecessor, the improvements are hugely obvious. Metro Exodus used a real-time lighting system in prior console versions as well, although the hardware wasn't capable of handing in anything more than a relatively basic GI pass. RTGI is totally transformative to the general look of the game - and the fact we're looking at a 60fps game (albeit one that can run at a very low internal resolution) is another remarkable aspect to the game.