https://www.gamespot.com/articles/call-of-duty-black-ops-4-not-having-a-campaign-is-/1100-6459076/

Unlike pretty much all of the previous Call of Duty games, this year's Black Ops 4 from developer Treyarch will not have a single-player campaign, at least not in the traditional sense.

In place of a single-player campaign, the game will offer an assortment of solo missions that focus on Specialist characters. These missions will have a similar style of bombastic set-pieces that Call of Duty games are known for, and there will be story elements divulged in these missions. So in that sense, there will be something in Black Ops 4 for players looking for a campaign-style experience. But it's not the kind of campaign fans are accustomed to.