How to make Player rotate up and down based on Camera up and down?

I have the below code which moves Player in camera direction and also rotates Player left and right (around Y axis) based on camera rotation.

But how can I also get it to rotate Player up and down, based on Camera up and down? (by "up and down", I mean tilting forward and backward around the X axis)

For some reason all of my approaches are failing. Can anyone please let me know a possible working solution?

Reason: I'm trying to make the Controller a Flying Controller.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Planey : MonoBehaviour
 {
     public Rigidbody r;
     public CapsuleCollider capsule;
     public Transform cameraTransform;
  
     //Base Movement
     public float horizontalInput;
     public float verticalInput;
     public Vector3 moveDirection;   
     public int rotDegPerSecond = 720;
     public float speed;   
     public float clampXZValue;
 
     //GroundChecking
     public LayerMask groundLayerMask;
     public Transform groundCheckTransform;
     public bool isGrounded;
     public float groundCheckRadius = 0.25f;
     public float distanceToGround;
 
     
 
     void Awake()
     {
         r = GetComponent<Rigidbody>();
         capsule = GetComponent<CapsuleCollider>();
     }
 
     private void FixedUpdate()
     {
         GroundCheck();
         Move();
         StopSliding();        
     }
 
     void Move()
     {
         horizontalInput = Input.GetAxis("Horizontal");
         verticalInput = Input.GetAxis("Vertical");
 
         moveDirection = new Vector3(horizontalInput, 0.0f, verticalInput).normalized;
         moveDirection = (Quaternion.AngleAxis(cameraTransform.rotation.eulerAngles.y, Vector3.up) * moveDirection).normalized;
 
 
         if (moveDirection != Vector3.zero && moveDirection != Vector3.zero)
         {
             Quaternion targetRotation = Quaternion.LookRotation(moveDirection); //or moveDirectionRaw
             targetRotation = Quaternion.RotateTowards(transform.rotation, targetRotation, rotDegPerSecond * Time.deltaTime);
             r.MoveRotation(targetRotation);
         }
 
         Vector3 force = moveDirection * speed;
         r.AddForce(force, ForceMode.VelocityChange);
 
         //Clamping
         Vector3 velocityH = new Vector3(r.velocity.x, 0, r.velocity.z);
         Vector3 velocityV = new Vector3(0, r.velocity.y, 0);
         r.velocity = Vector3.ClampMagnitude(velocityH, clampXZValue) + velocityV;
     }
  
 
 
     void StopSliding()
     {
         if (moveDirection == Vector3.zero)
         {
             Vector3 zeroMe = new Vector3(0, r.velocity.y, 0);
             r.velocity = zeroMe;
         }
     }
 
     public void GroundCheck()
     {
         isGrounded = Physics.CheckSphere(groundCheckTransform.position, groundCheckRadius, groundLayerMask);
         
         RaycastHit groundHit = new RaycastHit();
         if (Physics.Raycast(transform.position, -Vector3.up, out groundHit))
         {
             distanceToGround = groundHit.distance;
         }
     }
 }