Yonder: The Cloud Catcher Chronicles (UP)

You can find shampoo bottles in chests or trade them with certain vendors around Gemea. Once you have one, open up your menu and use it to change the color of your hair. You will need to do this 10 times to get the trophy. You can also craft shampoo later in the game but it will require a lot of materials and it's easier to search them in chests and/or trade them.