Modern Warfare Multiplayer Pack brings an addition update and requires quite a bit of disc space to download.
The actual title update is rather hefty and brings with it new content and bug fixes. It requires 13GB on PS4, 18GB on Xbox One, and 48GB on PC. But that's not all, depending on your platform, you'll need to download additional updates.
And they're also hefty.
Modern Warfare Multiplayer Pack
Xbox users will specifically need to download a 9GB Multiplayer Pack. You will not be able to queue up for any multiplayer maps unless you download this first.
PS4 players will need to download a 13GB Spec Ops pack. Same rules apply for PlayStation players. It's been surprising for many players on how much space this update has taken up and you'll probably need to delete things or move things around if you want to fit it on your platform.
The patch brought the new crossbow. However, you'll need to unlock it by using a Marksman Rifle with a Reflex Optic and get five kills in 25 different matches.