I have this code and I'd like to add a shotgun to the game by slightly modifying the code. I've looked online for any example but everything I find is for FPS not a TDS.

void Shoot ()
{
    timer = 0f;

    gunAudio.Play ();

    gunLight.enabled = true;

    gunParticles.Stop ();
    gunParticles.Play ();

    gunLine.enabled = true;
    gunLine.SetPosition (0, transform.position);

    shootRay.origin = transform.position;
    shootRay.direction = transform.forward;

    if (Physics.Raycast (shootRay, out shootHit, range, shootableMask))
    {
        EnemyHealth enemyHealth = shootHit.collider.GetComponent <EnemyHealth> ();
        if(enemyHealth != null)
        {
            enemyHealth.TakeDamage (damagePerShot, shootHit.point);
        }
        gunLine.SetPosition (1, shootHit.point);
    }
    else
    {
        gunLine.SetPosition (1, shootRay.origin + shootRay.direction * range);
    }
}

I have a basic understanding of most of this code. I don't quite understand how shootRay.direction understands transform.forward means always the front of player. As DMGregory stated adding a variable of some sort that runs through a for loop firing multiple different angles (or simply different coordinates if making angle rays is over my head) is the route I first thought of but I cannot find a way to implement it. I'm having issues with understanding how to manipulate ray coordinates because they cannot be changed by floats which is the extent of my current knowledge of problem solving.