AnimationController.cs

public class AniamtionController : MonoBehaviour
{
    [SerializeField] private PlayerControllerHolder playerControllerHolder;

    private void Start()
    {
        if (playerControllerHolder == null)
            return;

        playerControllerHolder.PlayerController.PlayAnimation();
    }
}

PlayerControllerAssigner.cs

public class PlayerControllerAssigner : MonoBehaviour
{
    [SerializeField] private PlayerController playerController;
    [SerializeField] private PlayerControllerHolder playerControllerHolder;

    private void Start()
    {
        if (playerControllerHolder != null)
        {
            playerControllerHolder.PlayerController = playerController;
        }
    }
}

PlayerControllerHolder.cs

[CreateAssetMenu(fileName = "PlayerControllerHolder", menuName = "Scriptable Objects/PlayerControllerHolder")]
public class PlayerControllerHolder : ScriptableObject
{
    public PlayerController PlayerController;
}