https://www.gamespot.com/articles/battlefield-1-in-the-name-of-the-tsar-updates-patc/1100-6453125/

Battlefield 1's latest expansion, In the Name of the Tsar, is out today for some players. Alongside it, a new update has arrived for everyone that includes some fixes, features, and more.

In the Name of the Tsar content is available to Premium Pass and Battlefield 1 Revolution owners right now; everyone else will be able to purchase the expansion on September 19. Even if you don't own the DLC, however, the new update--which is mandatory to play online--will allow you to watch In the Name of the Tsar matches through Spectator mode.