Mods for Xbox have to be converted from the PC mods and not all work because of the hardware limitations.
I grabbed a modded NTSC-U copy of the goty edition for Xbox years ago (I already had the retail PAL goty).
The modded edition was labelled "Perfect Edition" or something like that, some mods were enabled by default but only ones that didn't create serious stability issues, other non-active mods were included on the disc image of the game in an extra folder iirc, with text instructions on how to implement them etc.
That's for Morrowind, I've never played Oblivion with any mods. Or Skyrim.