Accessing new content and getting loot is the way you play The Division 2. For some chests and things that you come across you need keys, such as Cleaners and Riker chests which you can find during campaign missions. or by completing checkpoints in The Warlords of New York. There is a unique key that many players will probably call Ivory Keys, and you need to collect eight of them to unlock the special chest.
Ivory Keys are a rare item that you can acquire in The Division 2. Unlike other faction keys, you must find them by eliminating Hunters. Hunters are the powerful NPCs that you can find in the game, but they are hidden away. For example, Civic Center hunters are summoned by entering a laundromat, following a special code on the wall of an apartment, and interacting with specific corpses to summon it.
After removing it, you receive unique masks related to these hunters and an ivory key. Previously, players only had one chance to get an Ivory Key from a Hunter, meaning you had to join another player's game to chase the Hunters multiple times to get them to drop a key. Now among the hunters in the game you should be able to receive all eight in your game.
When you are done getting the eight Ivory Keys, you must return to the White House to find the large container of weapons to use. This particular box is located to the right of the entrance. It's in the same little nook where you can change your character's physical appearance, to the right of the Vendor and Quartermaster. Approach with the eight keys to open it and receive the Shield Splinterer, an F2000 assault rifle.
You want to go after these keys after completing the main game. There are even more Ivory Keys available with new Hunters added with the Warlords of New York expansion.