Application.CaptureScreenshot on a Texture2D?

You need to use RenderTexture (pro only) to do that. create a script and apply it to camera and copy the code to a IEnemurator function in that script.

         RenderTexture.active = camera.targetTexture;
         Texture2D texFront = new Texture2D(camera.targetTexture.width,camera.targetTexture.height,TextureFormat.RGB24,false );
         texFront.ReadPixels(new Rect(0,0,512,512), 0, 0);
         texFront.Apply();
         
         yield return null;
         Manager._instance.side = -1;
         _shirtHandler.LoadPattern();
         
         
         yield return new WaitForEndOfFrame();
         
         camera.Render();
         
         RenderTexture.active = camera.targetTexture;
         Texture2D texBack = new Texture2D(camera.targetTexture.width,camera.targetTexture.height,TextureFormat.RGB24,false );
 
         texBack.ReadPixels(new Rect(0,0,512,512), 0, 0);
         texBack.Apply();

you can create a rendertexture at run time or create one and apply it earlier to the camera.... Note that you have to replace the value 512 in my code with what ever height and width you screenshot has.