To unlock the "Heirloom" trophy in Life is Strange 2 - Episode 2: Rules, you need to find the fourth optional collectible in the Eriksens' house.
The situation for this collectible is story-related and unavoidable, but the answer you give to the problem decides whether you receive the collectible. After entering the Eriksen's house, you'll enter into a conversation with Chris. He'll task you with sorting out his toys into heroes and villains.
Put Dino, Bear, Warrior, and Pirate into the Heroes category. Put Insectoid and Car into the Villains category. Confirm your choices with Chris and he'll reward you with the Interstellar Traveller toy collectible.