According to the official materials Call of Duty: WW2's multiplayer will support up to 48 players. Perhaps the most interesting element though is that players will be able to socialise around a central in-game hub called Headquarters. Like the Tower in Destiny, the short teaser of the new feature showcases what looks like a large beach-side base with players running around. As to what you can do there exactly we're not sure, but at the very least we can expect to be able to group up and join matches.
The 48 player thing might be limited to Headquarters, as standard Call of Duty matches with 18 players will probably be the norm. We can expect to find out more about the multiplayer side of the game at E3.
Call of Duty: WW2 is out November 3 on PC, PS4, and Xbox One.