To obtain the White Goats Gone Missing side adventure in The Legend of Zelda: Tears of the Kingdom, speak with Penn at the Tabantha Bridge Stable during the Potential Princess Sightings side adventure. For this quest, you’ll need to first speak with Chork who can be found near Penn. Next, follow the trail of Hylian Pine Cones to the southeast.
They will lead you to the goats who can be found grazing next to a giant tree. Penn will then check in with you and the quest will complete!