When Buy a used Xbox One with previous owners DL games on it....Can I make an account and ...

You can play them as long s it remains the person who bought the games "Home" console. If that person buys another Xbox One, you would lose those games.

Peace, J.R.

Yes, if you bought the Xbox used, then that means the previous owner set the console as their "Home" console, and when sold it, did not remove this designation. The previous owner at some point must have re-bought an Xbox One, so now whenever they purchase
a title on their account, their old Xbox still thinks that that owner owns it, so you essentially get whatever game they buy for free. Good deal on your end .

The games are tied to the original owners Xbox live account. I am sorry but you will probably need to buy the games on your Xbox live account or buy the physical disks of the games. There isn't much you can do as the games were bought on the previous owners
Xbox live account. Ah the joys of digital games.

Let me further elaborate on what Warrior Njal already said.

Your friend bought a used Xbox One. The previous owner probably has set the console as his "Home Console", which enables the console to share the previous owners games and Gold membership with anyone playing on that console.

If the previous owner sets a different console as their home console, or if the previous owner stops his Xbox Live subscription, your friend will stop being able to play online multiplayer, and the games he bought "preloaded" on the console will also stop
working.

So please make your friend aware, that if your friend payed extra money for digital download games on that used console, that he demands a refund for these games, as the previous owner can "disable" the download games any time.

Games your friend bought on disc from the previous owner, are safe, as well as games your friend bought on his own account.

it may also still be set up as the previous owners Home Xbox. If your friend bought it with access to digital downloaded games, the shock will come once the owner makes their new Xbox as the home one. Digital games can not be transfered to a new owner.