https://wccftech.com/xbox-series-x-game-upgrades-dlc/

Xbox Series X next-gen upgrades cannot be sold as paid DLC, according to a new report.

Video Games Chronicles reported that Microsoft is telling developers that next-gen upgrades cannot be sold as DLC, regardless of the participation in the Smart Delivery program. This doesn't mean, however, that all next-gen upgrades will be free, as publishers can choose to charge for physical game upgrades or sell cross-gen bundles like 2K is doing with NBA 2K21. Microsoft's goal is to offer publishers different options for how to sell their cross-gen games.