Call of Duty Modern Warfare 2 and 3 Content Does Not Carry Forward Into Black Ops 6

Call of Duty Black Ops 6 acts as a “fresh start for everyone,” developer Treyarch has confirmed.

https://www.ign.com/articles/call-of-duty-modern-warfare-2-and-3-content-does-not-carry-forward-into-black-ops-6