How to move my character forward relative to rotation?

I’ve been using this to move my character:

void FixedUpdate()
{
    float moveInput = Input.GetAxisRaw("Horizontal");
    rb.velocity = new Vector2(moveInput * moveSpeed * Time.fixedDeltaTime, rb.velocity.y);
}

What I want to do is have my y-velocity changed depending on the rotation of my player, instead of simply moving horizontally no matter what. I don’t know how I should go through this, so help would be appreciated.

@gazer500 I am not exactly sure what you are asking, but from what information you have given so far I think you want the character to move toward the transform.up (local y) vector. To be sure can you explain a bit more of the desired perspective/camera and the desired movement. Is there a game that exists with similar camera/movement controls? Can you upload a screenshot/short video capture of the current movement? If you would like to upload a video I have been doing screen capture software FRAPS and upload to streamable. Let me know if this helps.