Quick question. Does turning off Multiplayer Unranked Crossplay turn it off for zombies as well? I noticed that only MP and Warzone have the option, but not Zombies.
No. Here's how we wrote this up in the patch notes:
In Season 03, we're giving console players more granular options by separating the MP Ranked Play and Call of Duty: Warzone Ranked Play settings and adding a new Multiplayer-only setting for Quickplay, Featured, and Party Games matches.