Quaternion.AngleAxis

Description

Creates a rotation which rotates angle degrees around axis.

For more information see Rotation and Orientation in Unity. The magnitude of the axis parameter is not applied.

using UnityEngine;

public class Example : MonoBehaviour
{
    void Start()
    {
        // Sets the transform's current rotation to a new rotation that rotates 30 degrees around the y-axis(Vector3.up)
        transform.rotation = Quaternion.AngleAxis(30, Vector3.up);
    }
}