Upgrade to series x

If i upgrade from xb1 to series x/s do i keep the dlc’s I’ve bought? What about any bazaar items/battle pass unlocks?

Items are tied to your account not the system so yes you keep all of that.

Nice. What about a single player/offline map and character?

Im constantly playing either on my Series X or my Xbox One X, depending on my mood of being lazy on the couch. Or my gaming chair.
I have no issues continuing my Game between the 2.

Its all saved in the cloud to your account.
You don’t lose anything, its not like gta

Series x game experience is a lot better