Change Texture Shape of a texture through script

Update: After digging through endless forum posts, I've solved my original question of getting a URL to a skybox.

I hope this helps someone with the same problem!

 using System.Collections;
 using UnityEngine;
 
 public class LoadImageToSkybox : MonoBehaviour
 {
     public string url = "Your URL Here";
     public int CubemapResolution = 512;
     Cubemap c;
 
     private Texture2D source;
 
     /// <summary>
     /// These are the faces of a cube
     /// </summary>
     private Vector3[][] faces =
     {
         new Vector3[] {
             new Vector3(1.0f, 1.0f, -1.0f),
             new Vector3(1.0f, 1.0f, 1.0f),
             new Vector3(1.0f, -1.0f, -1.0f),
             new Vector3(1.0f, -1.0f, 1.0f)
         },
         new Vector3[] {
             new Vector3(-1.0f, 1.0f, 1.0f),
             new Vector3(-1.0f, 1.0f, -1.0f),
             new Vector3(-1.0f, -1.0f, 1.0f),
             new Vector3(-1.0f, -1.0f, -1.0f)
         },
         new Vector3[] {
             new Vector3(-1.0f, 1.0f, 1.0f),
             new Vector3(1.0f, 1.0f, 1.0f),
             new Vector3(-1.0f, 1.0f, -1.0f),
             new Vector3(1.0f, 1.0f, -1.0f)
         },
         new Vector3[] {
             new Vector3(-1.0f, -1.0f, -1.0f),
             new Vector3(1.0f, -1.0f, -1.0f),
             new Vector3(-1.0f, -1.0f, 1.0f),
             new Vector3(1.0f, -1.0f, 1.0f)
         },
         new Vector3[] {
             new Vector3(-1.0f, 1.0f, -1.0f),
             new Vector3(1.0f, 1.0f, -1.0f),
             new Vector3(-1.0f, -1.0f, -1.0f),
             new Vector3(1.0f, -1.0f, -1.0f)
         },
         new Vector3[] {
             new Vector3(1.0f, 1.0f, 1.0f),
             new Vector3(-1.0f, 1.0f, 1.0f),
             new Vector3(1.0f, -1.0f, 1.0f),
             new Vector3(-1.0f, -1.0f, 1.0f)
         }
     };
 
 
     private void Start() { // When the game starts, apply the skybox texture
         StartCoroutine(setImage());
     }
 
     IEnumerator setImage()
     {
         WWW www = new WWW(url);
 
         yield return www;
         Debug.Log(www.bytesDownloaded);
         Debug.Log(www.progress);
         Debug.Log(www.texture);
 
 
         source = new Texture2D(www.texture.width, www.texture.height);
         // we put the downloaded image into the new texture
         www.LoadImageIntoTexture(source);
 
         // new cubemap 
         c = new Cubemap(CubemapResolution, TextureFormat.RGBA32, false);
 
         Color[] CubeMapColors;
 
         for (int i = 0; i < 6; i++)
         {
             CubeMapColors = CreateCubemapTexture(CubemapResolution, (CubemapFace)i);
             c.SetPixels(CubeMapColors, (CubemapFace)i);
         }
         // we set the cubemap from the texture pixel by pixel
         c.Apply();
 
         //Destroy all unused textures
         DestroyImmediate(source);
         DestroyImmediate(www.texture);
         Texture2D[] texs = FindObjectsOfType<Texture2D>();
         for (int i = 0; i < texs.Length; i++)
         {
             DestroyImmediate(texs[i]);
         }
 
         // We change the Cubemap of the Skybox
         Material cubeMapMaterial = new Material(Shader.Find("Skybox/Cubemap"));
         cubeMapMaterial.SetTexture("_Tex", c);
         RenderSettings.skybox = cubeMapMaterial;
     }
 
     /// <summary>
     /// Generates a Texture that represents the given face for the cubemap.
     /// </summary>
     /// <param name="resolution">The targetresolution in pixels</param>
     /// <param name="face">The target face</param>
     /// <returns></returns>
     private Color[] CreateCubemapTexture(int resolution, CubemapFace face)
     {
         Texture2D texture = new Texture2D(resolution, resolution, TextureFormat.RGB24, false);
 
         Vector3 texelX_Step = (faces[(int)face][1] - faces[(int)face][0]) / resolution;
         Vector3 texelY_Step = (faces[(int)face][3] - faces[(int)face][2]) / resolution;
 
         float texelSize = 1.0f / resolution;
         float texelIndex = 0.0f;
 
         //Create textured face
         Color[] cols = new Color[resolution];
         for (int y = 0; y < resolution; y++)
         {
             Vector3 texelX = faces[(int)face][0];
             Vector3 texelY = faces[(int)face][2];
             for (int x = 0; x < resolution; x++)
             {
                 cols[x] = Project(Vector3.Lerp(texelX, texelY, texelIndex).normalized);
                 texelX += texelX_Step;
                 texelY += texelY_Step;
             }
             texture.SetPixels(0, y, resolution, 1, cols);
             texelIndex += texelSize;
         }
         texture.wrapMode = TextureWrapMode.Clamp;
         texture.Apply();
 
         Color[] colors = texture.GetPixels();
         DestroyImmediate(texture);
 
         return colors;
     }
 
     /// <summary>
     /// Projects a directional vector to the texture using spherical mapping
     /// </summary>
     /// <param name="direction">The direction in which you view</param>
     /// <returns></returns>
     private Color Project(Vector3 direction)
     {
         float theta = Mathf.Atan2(direction.z, direction.x) + Mathf.PI / 180.0f;
         float phi = Mathf.Acos(direction.y);
 
         int texelX = (int)(((theta / Mathf.PI) * 0.5f + 0.5f) * source.width);
         if (texelX < 0) texelX = 0;
         if (texelX >= source.width) texelX = source.width - 1;
         int texelY = (int)((phi / Mathf.PI) * source.height);
         if (texelY < 0) texelY = 0;
         if (texelY >= source.height) texelY = source.height - 1;
 
         return source.GetPixel(texelX, source.height - texelY - 1);
     }
 }

This worked! I needed to change my sky dynamically for a computer vision perception project. Here is a quick and dirty snippet applying this code to my use case. Note, I modified the CreateCubeMapTexture and Project methods to take the texture as parameter instead of using a class variable.

 volumeObject.GetComponent<Volume>().profile.TryGet(out sky);
 var c = new Cubemap(CubemapResolution, TextureFormat.RGBA32, false);
 Color[] CubeMapColors;
 for (int i = 0; i < 6; i++)
 {
      CubeMapColors = CreateCubemapTexture(CubemapResolution, (CubemapFace)i, _texture);
      c.SetPixels(CubeMapColors, (CubemapFace)i);
 }
 c.Apply();
 sky.hdriSky.Override(c);