The story campaign in Call of Duty: Black Ops 7 has numerous restrictions tied to its always-online nature, with no method of pausing levels. You'll also be booted from your game if you're idle for too long.
As detailed in IGN's just-published Call of Duty: Black Ops 7 campaign review (which rates the offering as a 6/10), the story experience — traditionally offered as a solo affair — is really more geared to being played via online co-op, which it supports for up to four people.