It may be available in a preview version of the Xbox Windows app.
Microsoft is introducing a new feature in the Xbox app for Windows that will make it easier to determine if a game will run well on your PC.
This information comes with a label that says “Should play great on this PC” located below the blue install button on the game's showcase page. The feature is limited to a few games and is still under development. You can download the Xbox Insider Hub app to see for yourself and agree to receive preview versions of the Xbox app store.
It is unknown what criteria Microsoft uses to define a game that plays “great” on a PC, or whether there will be any layer between the other extreme of “great” and “not working at all”. It's possible that a game will run well at a lower FPS on a PC with certain specs, and it's unclear whether Microsoft will include such information in the "how does this game work" tag. From a quick review of the preview release, it appears that the games currently either have the "play great" tag or don't have them at all. We'll have to wait for Microsoft to say more to understand the details of how this new feature will work.
Every game in the Xbox app store already includes minimum specs and recommended requirements, meanwhile, this is still the solid reliable way to predict how a game will run on your computer.