On this page of our Little Nightmares 2 game guide, you will find the exact location and description of all the Hats you can earn in The Nome's Attic DLC.
Location: DLC The Nome's Attic.
To get to this Hat, beat all of the game with the character - Nom. It will lead you to the hat. All you have to do is go back into the room and climb the shelves. From them you get to the hat.
2nd hat - Mokujin mask
Localization: add-on granted for pre-purchasing the game.