The Legend of Zelda: Breath of the Wild broke the Zelda mold in many ways, from having an open world, to a unique take on the story, to the freedom of going where you want, when you want, it was a truly unique experience. But in a first, the game will also be the first Legend of Zelda game to have DLC. A two-part DLC is coming, and at the Nintendo E3 spotlight both parts were highlighted, and even given a release date.
The first part is called the Master Trials, and will feature new tests, new gameplay features like a special pin for the map, a harder difficulty mode, and new weapons and armor for you to use. This DLC will release June 30th.
The second is called the Champions Ballad, and seems to indicate that the four champions of the game (Mipha, Revali, Daruk, and Nabooru) will be playable in the game in some capacity. To further cement this, Nintendo revealed that Amiibo of the four champions are going to be available for purchase later this year. The Champions Ballad DLC will release Holiday 2017.