how to set rotation of an object through code in unity code example

Example 1: unity rotation to quaternion

using UnityEngine;public class Example : MonoBehaviour
{
    void Start()
    {
        // A rotation 30 degrees around the y-axis
        Quaternion rotation = Quaternion.Euler(0, 30, 0);
    }
}

Example 2: look rotation only on y axis in unity

var dir = PlayerMovement.playerTransform.position - transform.position;
        Quaternion LookAtRotation = Quaternion.LookRotation(dir);

        Quaternion LookAtRotationOnly_Y = Quaternion.Euler(transform.rotation.eulerAngles.x, LookAtRotation.eulerAngles.y, transform.rotation.eulerAngles.z);
        transform.rotation = LookAtRotationOnly_Y;