A new Series X|S icon is starting to appear on digital games that support Smart Delivery. According to this Xbox page, this icon means the game is optimized for the Series X|S.
The Optimized for Xbox Series X|S icon means the developer has done the extra work to take full advantage of the unique capabilities of Xbox Series X|S.
Ive seen a few, like the Ubisoft games for example are smart delivery and have the S/X optimized tags. But other games that I thought were smart delivery like Crash 4 don’t have the tag yet. Hopefully all games are tagged accordingly soon.
Crash 4 is actually not getting a Series X version. Even the boxart has a disclaimer with something like “Xbox One game playable on Series X”.
Actually when the game launched the store description said that it supported Smart Delivery, even though the next-gen version is not officially confirmed yet.