Call of Duty: Black Ops 6 will require an internet connection at all times, even if you're just playing the game's single-player campaign, Activision has revealed.
On the official support page for the game (via Wario64), Activision says that in order to "deliver the highest-quality visuals" for Black Ops 6, the game uses texture streaming, which is effectively a system by which textures are downloaded and streamed as required rather than loaded all at once.
As you've probably already spotted, however, texture streaming requires a constant internet connection, and so even if you're playing Black Ops 6's campaign mode or you're playing local multiplayer, you're going to need a stable online connection in order to play.

Obviously, needing an internet connection to play online with other players is understandable, but needing one for the campaign does feel a little off, even for the reason given.
Activision does, however, point out that you won't need an Xbox Game Pass or PlayStation Plus subscription to play Call of Duty: Black Ops 6's campaign. You will need a subscription if you're playing multiplayer, though (unless you're on PC, of course).
On the same support page, Activision also clarifies its position on split-screen play in Black Ops 6. Essentially, it'll be available on current-gen consoles but won't be on PS4 or Xbox One in order to "ensure performance integrity".
Call of Duty: Black Ops 6 is the next game in both the Call of Duty series and the Black Ops sub-series. As we learned during yesterday's Xbox showcase, it'll launch on October 25th across PC and consoles.
It'll be the first Call of Duty game to be available on Xbox Game Pass on the day of its release, although depending on your Game Pass subscription, you may or may not be able to access certain elements of the game.
In essence, Game Pass Ultimate subscribers can enjoy all of Black Ops 6 on their PC or console, as can Game Pass PC subscribers. Game Pass Console subscribers will only get access to the campaign, and Game Pass Core subscribers won't be able to access Black Ops 6 via their subscriptions.
Call of Duty: Black Ops 6 launches on October 25th on PC, PlayStation, and Xbox. Watch this space for more info.