@shikamaru317 In case you still want more confirmation.
https://www.eurogamer.net/articles/digitalfoundry-2020-this-is-how-xbox-series-s-back-compat-really-works
...bringing titles that ran at native 720p up to 1440p. While this doesn't match the max 4K we saw on Xbox One X, there is the potential for improved performance elsewhere thanks to the much faster Zen 2 CPU architecture. In scenarios where Xbox One X was limited by its Jaguar CPU cores, Series S has much more headroom.
It's already been confirmed that the ways in which Series S and Series X handle Xbox One titles varies. Only the Series X will benefit from Xbox One X enhancements to existing games - which typically boils down to resolution boosts, higher quality textures and other graphics-driven effects. Xbox Series S brings its additional horsepower to bear in improving the experience of Xbox One S titles instead. This is more limiting in some respects (a game hard-coded to run at 900p will not run any higher on Series S, for example) but the new console benefits from increased resolutions in games that use dynamic resolution scaling, as well as improvements to texture filtering quality. Obviously, running games from solid state storage reduces loading times significantly, while the Auto HDR feature we've seen running on Series X also features on Series S - all games should present nicely on HDR screens, whether they natively support high dynamic range or not.
"We designed the Series S to enhance the Xbox One S games in a way that the Xbox One X can't do," system architect Andrew Goossen tells us. "We made it easy for existing Xbox One S games to be updated to run with double the frame-rate when played on Series S as well. When games are updated, existing games can query to determine whether they're running on the new console. And in terms of the performance, the Series S provides well over double the effective CPU and GPU performance over the Xbox One, making it pretty straightforward for the games to do this. And in fact, the Series S GPU runs the Xbox One S games with better performance than the Xbox One X."
...We had one triple-A title where doubling the frame-rate really worked perfectly, except that the crowd animation was twice as fast as normal. And so, those sorts of fixes are typically very, very easy for developers to go fix. We're working with game developers and publishers to update [their titles]. It'll basically be select games that run at a doubled frame-rate on the Series S."
So, as we understand it, existing Xbox titles can be enhanced for both Series S and Series X in different ways - the compatibility team can step in with its own specific type of magic, opening the door to running 30fps games at 60fps and 60fps titles at 120fps. Alternatively, developers now have the tools to see where their existing Xbox One games are running - and if it's a Series S or Series X machine, aspects like doubling the frame-rate become possible (and perhaps other features could be enabled too) - all without having to 'port' their games to the next-gen platform...
Doesn't seem like there'll be much attempt if any to reach 4K gaming on Series S. But that's on brand with what they're selling. And given all the other benefits, I think it's a fairly good tradeoff.