Welcome to the Game Universe. My name is Joshua Ewell and I am the Solo Indy Developer for the games produced here. I build video games using Unreal Engine 4.
The Xbox Series X can be used to attach the same USB drive from your Xbox One and to instantly access the loaded games. You're not going to be able to access Xbox Series X games from an external hard drive, but it's always worth plugging one into your machine. In reality, you can use the same one that was plugged into your Xbox One and start playing the same games right away.
Xbox Series X product management director Jason Ronald revealed during the new episode of Inside Xbox that you would be able to unplug the hard drive from the old console holding Xbox One software, plug it into Xbox Series X and play the same games playing from the external drive.
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This ensures that the 1 TB disk on Xbox Series X and the available 1 TB expansion card should be allocated for games of the next decade, and anything else can be placed on an external USB drive alone.
However, you can also store Xbox Series X games on an external linked disk, but you would need to pass them to either the expansion card or the internal SSD until they are accessible due to the speed needed.
And support for games from the original Xbox, these storage features will keep you from needing to uninstall games to make room for new ones. Many Xbox One titles including Halo 5: Guardians and Call of Duty: Modern Warfare now reach 100 GB with enabled post-launch patches and such file sizes are expected to become the standard as resolutions and performance improves.