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

The account that bought the games needs to be on your xbox in order for another account to access them.

You console needs to be set as your "home" console as well,that's assuming you have a xbox one or series X/S.

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.