How to Buy They Shall Not Pass
If you want to buy the They Shall Not Pass DLC for Xbox One, PS4 or PC, you've got two options.
The first way is through the game's Premium Pass. The Battlefield 1 Premium Pass is the $50 season pass that nets you Battlepacks, premium queues, unique dogtags, all of DICE's Battlefield 1 expansion packs, and two weeks early access to all upcoming DLC packages.
For more on the merits of the Battlefield 1 Premium Pass, take a look at our reasons to and not to buy it right now.
Your other option is to buy the DLC a la carte as a standalone piece of content.