load and switch sprite tiles programatically?

Hi, i am trying to create a top down game where a player's appearance can be changed dynamically during run time, as they switch armor, weapons, etc. to do this, i need to combine different sprites based on in-game actions.

for example, if the player switches weapons, i would keep the same armor sprite, but load a different weapon sprite and display that instead.

i plan on having all these sprites (Armor, weapons, etc) saved as tiles. right now, i'm simply trying to load a sprite tile i've created, and switch between tiles (select which tile to display) in the update method. however, i'm unable to do so. i don't know how to switch tiles:

 public class Main : MonoBehaviour {
     SpriteRenderer rend;
     Sprite backSprite; 
 
     void Start()
     {
         backSprite = Resources.Load("tiles", typeof(Sprite)) as Sprite;
         GameObject obj = new GameObject("Wiz");
         rend = obj.AddComponent(typeof(SpriteRenderer)) as SpriteRenderer;
         rend.sprite = backSprite;
     }
 
     void Update()
     {
         //switch between tiles here:
 
     }
 }

does anyone know how to modify this code so that it cycles through all the tiles in my "tiles" sprite sheet? i would also like to be able to select specific tiles so that i can switch to an arbitrary tile in the sprite sheet at any point in time.

thanks!