Will old Xbox One DLC codes work on Series X?

[Pieter]

I have a couple dlc codes for RDR2 and Fallout 4 so will i be able to re-use them. My brother and i will probably use the same account except ill be on Series X and he will be on Xbox One so we wont be able to play at the same time so it would help if it will be possible to re input these codes on a new account