https://wccftech.com/monster-hunter-world-producer-300-people-worked-on-iceborne-capcom-wants-to-push-the-franchise-further/

Once in a while, CAPCOM interviews its own game developers on the company's official website. This time, Monster Hunter World producer Ryozo Tsujimoto discussed the game's incredible success between the base game and the recently released Iceborne expansion. For instance, Tsujimoto revealed that Monster Hunter World Iceborne had more than 300 developers working on it.

It depends on the phase, but we have over 300 people working on the game. Capcom’s game development is split up into two large groups, and the Iceborne team is part of Consumer Games Development Division 2, which has around 700 people, so you can understand the scope of World’s team from that.