Limiting the rotation of x-axis

Hello to all, I.m here to ask something about limiting the rotation of the child camera from x axis. i tried adding the clamp inside the Rotate() but it wont work. I tried the google search but still i cant figure out why it wont work. I am replicating the resident evil 5’s camera control. I have a character that needed to limit the rotation of child camera’s x from 0 to 30 only. How can i do that? Please help me.
I’ll show my code:

void Start()
    Screen.lockCursor = true;

    ////Get the name of Player and Main Camera tag
    cameraGO = GameObject.FindGameObjectWithTag("MainCamera");
    cameraTargetGO = GameObject.FindGameObjectWithTag("Camera Target");
    localPlayerGO = GameObject.FindGameObjectWithTag("Local Player");

void LateUpdate()
    xRotation = Input.GetAxis("Mouse X") * Sensitivity;
    yRotation = -Input.GetAxis("Mouse Y") * Sensitivity;
    //Rotate the character along y-axis
    localPlayerGO.transform.Rotate(0, xRotation, 0);
    //Rotate the Camera along x-axis
    cameraTargetGO.transform.Rotate(yRotation, 0, 0);


Try this:

  cameraTargetGO.transform.Rotate(yRotation, 0, 0);
  var current = cameraTargetGO.transform.rotation.eulerAngles;
  cameraTargetGO.transform.rotation = Quaternion.Euler(Mathf.Clamp(current.x, 0, 30), current.y, current.z);