Is it worth downloading games onto a HDD in advance of Series X delivery.

I've downloaded games and moved them to my HDD ahead of the new console coming. However, games for the new console (Call of Duty for instance) won't download the next gen versions. That said, it's easier downloading this gens versions that you'll play on
now and then just download the next gen games at release. I've been downloading RDR2 and Forza Horizon 4 today so I can move them over to my HDD tomorrow and be ready for Tuesday so it's certainly helpful in that sense.

It'd probably be smarter to use a hdd and bring them over

And then individually bring the games you play most onto the internal drive if you do not want all of them to be patched

The series x will use smart.delivery to update the ones with smart delivery to update to series x version if available and qualify for smart delivery

Well first you need to download the patch are you forgetting the smart delivery update ?

Smart delivery is designed to download the correct version for your console

In this case series s

Optimized for the hdd space you do have

So you got the series s upgrade not the HD series x upgrade which is a good thing since you have hdd space limitation

I have the same question. I have FH4 and Gears 5 on external hdd and i play on Xone X. What will happen when I plug in my external hdd to my new x series x. WIll the new concol see games already installed on my external hdd and how then smart delivery
will work?? Must I change location of FH4 and Gears 5 from external hdd to internal ssd to use 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.