2D Texture outline using SetPixel()

Hi, I've got a script, which is drawing a customizable crosshair (like in CS:GO) using Texture2D and SetPixel(). There is only one thing that is missing - outline. How to create an outline for this crosshair? Ofc the size needs to be customizable.

 using UnityEngine;
  
 [ExecuteInEditMode]
 public class Crosshair : MonoBehaviour
 {
     public Texture2D crosshairTex { get; private set; } // Crosshair texture
  
     [Range(0f, 50f)] public uint size = 14; // Crosshair size
     [Range(0f, 10f)] public uint thickness = 2; // Crosshair thickness
     [Range(0f, 25f)] public uint gap = 6; // Crosshair gap
  
     public Color32 crosshairColor; // Crosshair color
     public uint customColor;
     public byte redColorValue;
     public byte greenColorValue;
     public byte blueColorValue;
     public byte alphaColorValue;
  
     public bool dot = false; // Crosshair dot
     public bool refresh = false;
  
     private void Start()
     {
         Refresh();
     }
  
     private void Update()
     {
         //if (refresh)
         //{
         //    Refresh();
         //    refresh = false;
         //}
  
         Refresh();
     }
  
     private void CheckThickness()
     {
         if (thickness % 2 == 0 && gap % 2 == 1) // Thickness even, gap odd
         {
             gap--;
         }
  
         else if (thickness % 2 == 1 && gap % 2 == 0) // Thickness odd, gap even
         {
             gap++;
         }
  
         if (thickness > gap) // Fix crashing when pixels are overwriting
         {
             gap = thickness;
         }
     }
  
     private void CheckColor()
     {
         if (customColor == 0)
         {
             crosshairColor = Color.red;
         }
         else if (customColor == 1)
         {
             crosshairColor = Color.green;
         }
         else if (customColor == 2)
         {
             crosshairColor = Color.yellow;
         }
         else if (customColor == 3)
         {
             crosshairColor = Color.blue;
         }
         else if (customColor == 4)
         {
             crosshairColor = Color.cyan;
         }
         else if (customColor == 5)
         {
             crosshairColor = new Color32(redColorValue, greenColorValue, blueColorValue, alphaColorValue);
         }
     }
  
     private void Refresh()
     {
         // Fix thickness and gap diff
         CheckThickness();
         CheckColor();
  
         uint s, g, t;
  
         s = size;
         g = gap;
         t = thickness;
  
         string crosshair = "";
         g += t;
         float se = (2 * s + g) / 2f;
         uint sC = 2 * s + (g - t);
  
         crosshairTex = new Texture2D((int)sC, (int)sC, TextureFormat.RGBA32, false);
  
         for (int k = 0; k < s; k++)
         {
             for (int i = 0; i < se - t; i++)
                 crosshair += "0";
  
             for (int i = 0; i < t; i++)
                 crosshair += "Y";
  
             crosshair += "\n";
         }
  
         for (int i = 0; i < (g - 2 * t) / 2; i++)
             crosshair += "\n";
  
         for (int k = 0; k < t; k++)
         {
             for (int i = 0; i < s; i++)
                 crosshair += "X";
  
             for (int i = 0; i < g - t; i++)
                 crosshair += "0";
  
             for (int i = 0; i < s; i++)
                 crosshair += "X";
  
             crosshair += "\n";
         }
  
         for (int i = 0; i < (g - 2 * t) / 2; i++)
             crosshair += "\n";
  
         for (int k = 0; k < s; k++)
         {
             for (int i = 0; i < se - t; i++)
                 crosshair += "0";
  
             for (int i = 0; i < t; i++)
                 crosshair += "Y";
  
             if (k != s - 1)
                 crosshair += "\n";
         }
  
         for (int ys = 0; ys < crosshairTex.height; ys++)
             for (int xs = 0; xs < crosshairTex.width; xs++)
                 crosshairTex.SetPixel(xs, ys, new Color(0, 0, 0, 0));
  
         int x = 0; int y = 0;
         var crosshairARR = crosshair.Split(new char[] { '\n' }, System.StringSplitOptions.None);
         foreach (string cStr in crosshairARR)
         {
             foreach (char cChar in cStr)
             {
                 if (cChar == 'Y' || cChar == 'X')
                     crosshairTex.SetPixel(x, y, crosshairColor);
                 else
                     crosshairTex.SetPixel(x, y, new Color(0, 0, 0, 0));
                 x++;
             }
             x = 0;
             y++;
         }
  
         if (dot == true)
         {
             for (int yk = 0; yk < thickness; yk++)
                 for (int xk = 0; xk < thickness; xk++)
                 {
                     crosshairTex.SetPixel((int)(crosshairTex.width / 2 - (thickness / 2) + xk), (int)(crosshairTex.width / 2 - (thickness / 2) + yk), crosshairColor);
                 }
         }
  
         crosshairTex.Apply();
     }
  
     void OnGUI()
     {
         // Crosshair
         GUI.DrawTexture(new Rect(Screen.width / 2f - crosshairTex.width / 2f, Screen.height / 2f - crosshairTex.height / 2f, crosshairTex.width, crosshairTex.height), crosshairTex);
     }
 }