They Shall Not Pass delivers some new vehicles to the game.
One new vehicle is a super-heavy tank from France called the Char 2C.
The Char 2C was developed during the war. And while it eventually rolled off the assembly line, the Char 2C was deployed after World War I ended. You can get a feel for it in the footage from the Battlefield 1 CTE below.
This tank joins the likes of the Dreadnaught, zeppelin, and armored train as a behemoth class vehicle.
The other vehicle is the Assault Tank Gun, also known as the St. Chamond. The Assault Tank Gun "was most heavily armed allied tank of the war" and like the Char 2C, its of French origin.
Thanks to the CTE we know the St. Chamond has the ability to call in an artillery strike onto your position via a bird.
DICE is reportedly thinking about bringing the DLC vehicles to the vanilla version of the game though this would likely be done through a custom game mode.