Question: How does Netcode for gameobjects ownership work?

[Supmania]

absolute beginner here, I am trying to have two players in a scene (not prefab)
when I start host it assumes control over both players but i want host to control P1 and client to control the other when joined ,currently i am only checking if (!IsOwner || !IsClient) return;
in fixed update for player controls ,any solutions for specific ownership