Last month, Atomic Heart developer Mundfish responded on Twitter to reveal that its upcoming FPS would run at a dynamic 4K / 60FPS on Xbox Series X and PS5. At the time, the team didn't tell us how Xbox Series S would handle things, but a new dev interview has now dropped all the juicy details.
To get to the point; Atomic Heart is aiming for "Full HD and 60FPS" on Xbox Series S consoles. That's 1080p / 60FPS, which sounds like a reasonable target for maintaining a smooth frame rate on Series S.
Elsewhere, the interview touches on a few other details — like the game's comparisons to BioShock and DOOM — but the other real noteworthy point here is that ray tracing is missing at launch. The team says that the console version of Atomic Heart won't contain RT "for now", and no future plans for the feature were spoken of.
At present, just the one graphical mode is available in Atomic Heart, then, but at least it's aiming for 60FPS on all current-gen machines. The team didn't talk about the Xbox One version here, but it's safe to expect 30FPS performance on last-gen Xbox consoles.