using UnityEngine;

public class rotation_demo : MonoBehaviour

{

    Quaternion rot;

    void Start()

    {

        rot.eulerAngles=new Vector3(45,0,90);

    }

}

Quaternion rot = Quaternion.Euler(V3.x, V3.y, V3.z);

Quaternion rotation = Quaternion.LookRotation(Vector3 forward, Vector3 up);