Can I move a game that I bought from one account to another? Xbox Series S

Nothing can be transferred between accounts.

What games are you transferring? Which consoles are involved? If it's transferring from, say, a Series X/S to an Xbox One, then it may be because the games are S/X versions.

As to the expansion pack, I believe that is only available to the account that bought it and the console that account is on...it can't be transferred to another account on another console

Hi,

Both Series X/S games and Xbox One games that been optimised (I'm British) for Series X/S must be installed on either the internal storage or the expansion card. They can not be run from a USB connected storage device. My optimised Series X/S Xbox One games
were moved to my Expansion card during their update.

Thank you for the reply.

The FAQ states the following:

• If you’re playing from disc on Xbox Series X|S, you’ll need to keep the disc inserted to play that game.
  

This implies if I bought a disc and installed on my xbox one, I would require the disc to play on my Series S. However the Series s is discless. I don't understand how a physical disc can state smart delivery for the Series S.

I just bought a brand new Xbox One X, but when I go to the store, Flight Simulator and other Xbox Series X/S games say they are "not playable on this device" and I can't get Flight Simulator to install on my brand new Xbox One X because it says it's "not compatible". Very frustrating.

So you bought an Xbox One X and expected to be able to play an Xbox Series X game on it?

Why would a game made for an Xbox Series X work on an Xbox One X?

If you want to play Xbox Series X/S games I would take your brand new Xbox One X back to the store you bought it and see if they will take it back and you could try and buy an Xbox Series S (Series X consoles are very hard to find, but a Series S can be found fairly easilly)