2d look at in unity code example

Example 1: unity 2d looka tt mouse

void Update() {
     Vector3 dir = Input.mousePosition - Camera.main.WorldToScreenPoint(transform.position);
     float angle = Mathf.Atan2(dir.y, dir.x) * Mathf.Rad2Deg;
     transform.rotation = Quaternion.AngleAxis(angle, Vector3.forward);

Example 2: 2d look at unity

//Look at 2D job using the unity jobs system
struct LookAtJob : IJobParallelForTransform
{
    public NativeArray<Vector2> targetPositions;
    public void Execute(int index, TransformAccess transform)
    {
        Vector2 dir = targetPositions[index] - (Vector2)transform.position;
        float angle = math.degrees(math.atan2(dir.y, dir.x));
        transform.rotation = Quaternion.AngleAxis(angle, Vector3.forward);
    }
}