To unlock the "Ranger" trophy in Life is Strange 2, you need to find the fourth collectible in the first episode. Well, it's technically the fourth, but you can actually find it after you find the first one.
After your first night out in the woods you will be headed towards a gas station. Before approaching the station, head right past the parked cars and head to the back of the station. Back there against the back wall of the station is a fake Haloween pumpkin on top of a chopped log. Between that and a long stack of chopped logs you should see a prompt labelled "Box". After the cutscene, make sure to pick up the feather where the box was. The trophy will then unlock. Make sure to get this before setting up your food and map on the picnic bench outside the gas station.
Screenshot for reference: