The main things that take up space on Xbox One are games and apps. If your Xbox fills up, make space by uninstalling stuff you’re not using.

Any data for your games and apps (preferences, saved games) syncs online when you sign in to Xbox Live. So when you reinstall a deleted game or app, your saved data comes right back with it.

https://support.xbox.com/en-GB/xbox-one/console/manage-storage