Can't play offline

Like stated in another post above you would need to put your console into offline mode to allow this.

Also like stated above there are games that are only online games like destiny 2 and fortnite and games like that, these will not work while in offline mode.

Here is a support article link that will explain all of this to you.

Playing Xbox One while offline

You have to switch the console to Offline mode to ensure it still works when you have no internet connection otherwise it will continue to try and connect and fail.

If you haven't tried that already.

I have my Xbox One X set as my home Xbox but I still can't play any of my downloaded or digital games off-line.

Do you have any example games that you can share with us, where you are having a problem?

I cant think of any of my games that are digital that work offline. The only ones that work offline for me are the ones I have the disk to and then some of them dont either.

most games require internet connection to download / update etc

and if the game is online based to play that will require constant internet connection.