How to make the camera move up and down

I have a script to move the player with the camera rotates left right but can't up down does anyone know how to do this?

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 namespace SG
 {
     public class CameraHandler : MonoBehaviour
     {
         public Transform targetTransform;
         public Transform cameraTransform;
         public Transform cameraPivotTransform;
         private Transform myTransform;
         private Vector3 cameraTransformPosition;
         private LayerMask ignoreLayers;
 
         public static CameraHandler singleton;
 
         public float lookSpeed = 0.1f;
         public float followSpeed = 0.1f;
         public float pivotSpeed = 0.03f;
 
         private float defaultPosition;
         private float lookAngle;
         private float pivotAngle;
         private float minimumPivot = -35;
         private float maximumPivot = 35;
 
         private void Awake()
         {
             singleton = this;
             myTransform = transform;
             defaultPosition = cameraTransform.localPosition.z;
             ignoreLayers = ~(1 << 8 | 1 << 9 | 1 << 10);
         }
 
         public void FollowTarget(float delta)
         {
             Vector3 targetPosition = Vector3.Lerp(myTransform.position, targetTransform.position, delta / followSpeed);
             myTransform.position = targetPosition;
         }
 
         public void HandleCameraRotation(float delta, float mouseXInput, float mouseYInput)
         {
             lookAngle += (mouseXInput * lookSpeed) / delta;
             pivotAngle -= (mouseYInput * pivotSpeed) / delta;
             pivotAngle = Mathf.Clamp(pivotAngle, minimumPivot, maximumPivot);
 
             Vector3 rotation = Vector3.zero;
             rotation.y = lookAngle;
             Quaternion targetRotation = Quaternion.Euler(rotation);
             myTransform.rotation = targetRotation;
 
             rotation = Vector3.zero;
             rotation.x = pivotAngle;
 
             targetRotation = Quaternion.Euler(rotation);
             cameraPivotTransform.localRotation = targetRotation;
 
         }        
     }
 }