Changing the speed and accelleration of a jump using the built-in Physics Rigidbody engine in Unity?

Hi all, I have started making a basic platformer game just for fun. Its going to be the style of the original Super Mario Bros game, but with 3d assets.

My problem is that I'm using a rigidbody and using code I have always used to make my player object jump. It seems really slow. I am using a capsule object, the standard size (which is 2 units height). I have played about with the mass, ive tried 1 and 40. And other than having to increase the 'jumpForce' value accordingly, it seems to have not changed the jump speed at all.

So I'm hoping there is a way to tweak the flight of the jump whilst still using the Rigidbody component, and if so how please?

If not, I think I'm able to write my own code to make the gravity etc, but this seems stupid since Unity is a well established game framework I expect other people have also needed to change it and I'm sure there is a way I just don't know about.

Hope someone can help me.

Many thanks!

PS (Here is the basic code I have to make the character jump):

 public class PlayerController : MonoBehaviour {
     Rigidbody rb;
     Vector3 faceRight = new Vector3(0, 90, 0);
     Vector3 faceLeft = new Vector3(0, -90, 0);
     float halfHeight;
 
     float speed = Constants.speed;
     float jumpForce = Constants.jumpForce;
 
     private bool IsGrounded()
     {
         return Physics.Raycast(transform.position, Vector3.down, halfHeight + 0.1f);
     }
 
     void Start () {
         halfHeight = GetComponent<Collider>().bounds.extents.y;
         rb = GetComponent<Rigidbody>();
         rb.transform.Rotate(0, 90, 0); // make the capsule face right at start.
     }
     
     void Update () {
         HandleKeys();
     }
 
     void HandleKeys()
     {
         if (Input.GetKey(KeyCode.A))
         {
             if (rb.transform.eulerAngles != faceLeft)
                 rb.transform.eulerAngles = faceLeft;
 
             rb.transform.Translate(Vector3.forward * speed * Time.deltaTime);
         }
         if (Input.GetKey(KeyCode.D))
         {
             if (rb.transform.eulerAngles != faceRight)
                 rb.transform.eulerAngles = faceRight;
 
             rb.transform.Translate(Vector3.forward * speed * Time.deltaTime);
         }
         if (Input.GetKeyDown(KeyCode.Space) && IsGrounded())
         {
             rb.AddForce(Vector3.up * jumpForce, ForceMode.Impulse);
         }
     }
 }