How can I divide www.texture data into multiple Texture2Ds?

Hello. I have some code to retrieve an image from the web and use it to create a Texture2D object...

 IEnumerator coDownloadWebScreenshotWithHeight(WebURL webUrl, Image image, int height)
     {
         string url = webUrl.URLWithHeight(height);
         WWW www = new WWW(url);
 
         yield return www;
 
         Texture2D imageTexture = new Texture2D(www.texture.width, www.texture.height, TextureFormat.ETC2_RGBA8, false);
         www.LoadImageIntoTexture(imageTexture as Texture2D);
         www.Dispose();
         www = null;
     }

The problem is, some of the images I'm downloading exceed the 4096x4096 texture size limit. So I would like to create multiple textures, each with a max size of 4096x4096, and then stitch them together after they're created. How can I divide the www.texture data into multiple chunks that I can use to create multiple Texture2D objects?

Thanks in advance for your help!