Call of Duty: Warzone 2.0 is currently available for preload, at least through Steam and Battle.net on PC. However, the console preload process might be a bit cumbersome at the moment.
See, if you want to download Warzone 2.0 on PlayStation 5, you will first need to go to the page for Call of Duty: Modern Warfare 2, hit the Options button to get to the Warzone 2.0 page, and go from there. For Xbox, it should...