I updated my code, my current problem is just that the movement of the player doesn't work anymore and I would like to know what I have to do so that I can adjust the height of the jump and that when this height is reached, gravity comes through again Code:

//Private Variables
private CharacterController _chaCont;
private float currentGravity;
private Vector3 finalMovement; 
//Globally delared
                               
//Public Variables
public float speed;
public float gravity;
public float jumpSpeed;

// Start is called before the first frame update
void Start()
{
    _chaCont = gameObject.GetComponent<CharacterController>();
}

// Update is called once per frame
void Update()
{
    if (Input.GetKeyDown(KeyCode.Space))
    {
       finalMovement = jump() + ApplyGravity();
    }
    _chaCont.Move(finalMovement * Time.deltaTime);
}

Vector3 ApplyGravity()
{
    Vector3 gravityMovement = new Vector3(0, -currentGravity, 0);
    currentGravity += gravity * Time.deltaTime;

    if (_chaCont.isGrounded)
    {
        if (currentGravity > 1f)
            currentGravity = 1f;
    }

    return gravityMovement;
}

Vector3 Movement()
{
    Vector3 moveVector = Vector3.zero;

    moveVector += transform.forward * Input.GetAxis("Vertical");
    moveVector += transform.right * Input.GetAxis("Horizontal");
    moveVector *= speed;

    return moveVector;
}

Vector3 jump()
{
    Vector3 jumpVector = Vector3.zero;

    jumpVector += transform.up * Input.GetAxis("Jump");
    jumpVector *= jumpSpeed;

    return jumpVector;
}

}