An insider under the nickname Liz, close to Destiny 2 developers, reports that in the future in the game will appear some activities designed for groups of 12 users.
The source does not specify what kind of activities we are talking about. At the current stage looter-shooter has activities only for groups of 3 and 6 people. It happened that gamers managed to find a bug and pass them in a group of 12 people, but Liz is referring to the official modes created by the developers.
Anyway, we are waiting for official announcements from Bungie.