The campaign is playable offline but you have to buy a disk version it says when you try and play it.
But when you go offline and you had just used the game with a connection it’s playable.
Even halo 5 had a campaign that didn’t need a connection for it to work the game isn’t really live service.
Even modern warfare they tried to make it’s so you need to be connected to the internet but that failed spectacularly and that game doesn’t need to connect to the internet first before it’s playable