Fallout 76 will be getting some new content via the Wastelanders and Nuclear Winter DLCs. The first DLC announced, Wastelanders aims to add more NPCs to the game and more RPG elements (like dialogue options), new weapons and armors and new main quests "of choice and consequence".

Fallout 76 - Official E3 2019 Wastelanders Gameplay Trailer

From the trailer's description:

Wastelanders is a massive free update to Fallout 76 that fundamentally changes the Wasteland, coming Fall 2019. One year after the opening of Vault 76, other humans have returned to Appalachia. Factions of Settlers and Raiders aim to make the world their own and claim a rumored fortune. Embark on a new main quest of choice and consequence, interact with characters and their unique stories, discover the faction settlements of Crater and Foundation, and collect powerful new weapons and armor. Your choices decide their fates.

The second piece of DLC announced, Nuclear Winter, will be the game's Battle Royale mode.

Fallout 76 - Nuclear Winter E3 2019 Dev Diary

Players will have to fight to the death in a new 52-player Battle Royale mode. The winning player will be Overseer of the newly unveiled Vault 52!

From the video's description:

Nukes have set the world ablaze and the battle to claim your spot as Overseer of Vault 51 has begun – will you be the last one standing or be consumed by the ring of fire? Rank up, unlock exclusive perks and build your C.A.M.P. to weather the storm in true Fallout fashion. Scavenge for weapons, supplies, and nukes to take on other players and creatures and earn unique cosmetic rewards.

Fallout 76 will get a free trial from June 10 through June 17, and players will also get a sneak peak at Nuclear Winter. You can learn more here.