Xbox one x Smart delivery ?

Yes. Xbox One games will be backwards compatible with the Series S/X. There are also games like Valhalla and Cold War that support Smart Delivery. With Smart Delivery, you can buy the games now on the One and you'll be able to download the Series S/X version
for free.

Microsoft introduces "Smart Delivery" with the Xbox Series X, which means, that if you own an existing game (like Minecraft in your example, or Gears 5) or a new game comes out for Xbox One and Xbox Series X with improved graphics on Series X, you won't
have to buy the game twice.

With Smart Delivery you will play the "enhanced" version on Series X, and the "normal" version on Xbox One.

For more info about Smart Delivery and other terms used with the Series X check this page: https://news.xbox.com/en-us/2020/03/16/xbox-series-x-glossary/

They are enhanced for the Xbox One X but Smart Delivery will deliver the best version of the game for your Series X console.

Hello,

Yes, Xbox one games that support Smart Delivery will just have to be purchased once. If you purchase the Xbox one version of a game, you’ll receive the Series X|S version (and vice versa) when you upgrade.

Smart Delivery for Xbox Series X|S FAQ

https://news.xbox.com/en-us/2020/06/15/what-is-smart-delivery-xbox-series-x/

Another good page explaining Smart Delivery, along with the current list of games that support it:

https://www.techradar.com/uk/news/xbox-smart-delivery-explained

Smart Delivery applies to both digital games and physical disks and your game progress will carry over, as normal, when you upgrade your console.

You also don’t need to do anything in terms of choosing a version to download, the system will automatically take care of that for you.

I hope this information helps, happy gaming!

When the Series X/S was sent out to testers pre-release, it was possible to install Xbox One versions of Smart Delivery Games....however, it seems it was made impossible for general release.

Found this from just after release:

"Update 18/11/2020: Microsoft has followed up with a statement, confirming that the decision to force Smart Delivery games to upgrade is indeed purposeful. So you’re locked out of playing your Xbox One version of any game with Smart Delivery. RIP your internal SSD space.

“Titles that support Smart Delivery will automatically detect what device you are playing on – Xbox Series S, Xbox Series X or Xbox One – and deliver the best version of the game available to you. We believe delivering the version of a game that has been specifically optimized and tailored to your device is the best user experience, which is why Smart Delivery was developed this way. For additional information on managing upgrades with Smart Delivery, please go to Xbox Support.”https://www.gamespew.com/2020/11/xbox-series-x-s-doesnt-force-you-to-upgrade-smart-delivery-games/