You are right, but Genshin Impact takes place in the fantasy world of Teyvat, which is home to seven nations, each of which is tied to a different element and ruled by a different god. The story follows the Traveler, who has traveled across countless worlds with their twin sibling before becoming separated in Teyvat. The Traveler travels in search of the lost sibling with their companion Paimon and becomes involved in the affairs of Teyvat's nations.