I don't play Call of Duty or Warzone, but I saw this on Reddit, and just wanted to share with as many people as possible.
In Warzone, PS4 players can opt out within the game, but Xbox One players cannot. However, there are settings within your Xbox One to limit multiplayer play to only Xbox Live users that can override the game settings.
The settings are as follows:
- Go to your xbox settings.
- Scroll to account and click on privacy and online safety
- Click on xbox live privacy
- Click on view details and customize
- Click on communications and multiplayer
- Change "you can play with people outside of xbox live" to block.
Sources:
From the limited reading I have done, it appears that it will require sufficient number of opted-out Xbox players to fill a lobby, but at least it is an option.
I hope this helps somebody out there.
Also: Perhaps someone with a Resetera account can share this in the thread regarding Warzone & Crossplay. I know members back and forth don't agree on most topics, but it would be helpful to share in this case.