GameController.cs

public class GameController : MonoBehaviour
{
    [SerializeField] private InputActionReference menuInput;
    [SerializeField] private InputActionReference exitMenuInput;

    [SerializeField] private UIController uiController;
    [SerializeField] private PlayerController playerController;
  
    private void OnEnable()
    {
        menuInput.action.performed += ShowUI;
        exitMenuInput.action.performed += HideUI;
        menuInput.action.Enable();
        exitMenuInput.action.Disable();
    }

    private void Start()
    {
        uiController.gameObject.SetActive(false);
    }

    private void OnDisable()
    {
        menuInput.action.performed -= ShowUI;
        exitMenuInput.action.performed -= HideUI;
        menuInput.action.Disable();
        exitMenuInput.action.Disable();
    }

    private void HideUI(InputAction.CallbackContext context)
    {
        uiController.gameObject.SetActive(false);
        playerController.EnableInput();
        menuInput.action.Enable();
        exitMenuInput.action.Disable();
    }

    private void ShowUI(InputAction.CallbackContext context)
    {
        uiController.gameObject.SetActive(true);
        playerController.DisableInput();
        menuInput.action.Disable();
        exitMenuInput.action.Enable();
    }
}

PlayerController.cs

[RequireComponent(typeof(CharacterController))]
public class PlayerController : MonoBehaviour
{
    [SerializeField] private float speed = 5f;


    private CharacterController _characterController;
    private InputSystem_Actions _inputActions;
    private Vector2 _input;

    private void Awake()
    {
        _inputActions = new InputSystem_Actions();
        _characterController = GetComponent<CharacterController>();
    }

    private void OnEnable()
    {
        _inputActions.Player.Enable();
        _inputActions.Player.Attack.performed += Attack;
    }

    private void OnDisable()
    {
        _inputActions.Player.Disable();
        _inputActions.Player.Attack.performed -= Attack;
    }

    private void Update()
    {
        GatherInput();

        Move();
    }

    private void Attack(InputAction.CallbackContext context)
    {
        Debug.Log("Attacking!");
    }

    private void Move()
    {
        Vector3 moveDireciton = transform.forward * speed * Time.deltaTime * _input.magnitude;
        _characterController.Move(moveDireciton);
    }

    private void GatherInput()
    {
        _input = _inputActions.Player.Move.ReadValue<Vector2>();
    }

    public void EnableInput()
    {
        _inputActions.Player.Enable();
    }

    public void DisableInput()
    {
        _inputActions.Player.Disable();
    }
}

UIController.cs

public class UIController : MonoBehaviour
{
    [SerializeField] private InputActionReference clickReference;

    private void OnEnable()
    {
        clickReference.action.performed += HandleClick;
    }

    private void HandleClick(InputAction.CallbackContext context)
    {
        if (context.ReadValue<float>() == 1f)
            Debug.Log("Clicking!");
    }

    private void OnDisable()
    {
        clickReference.action.performed -= HandleClick;
    }
}