public ActionResult DownloadFile() //you can put string html as parameter
        {
            string html = System.IO.File.ReadAllText(@"C:\Users\User\Desktop\test.html");// or you can pass it as parameter
            HtmlAgilityPack.HtmlDocument doc = new HtmlAgilityPack.HtmlDocument();
            doc.LoadHtml(html);
            var htmlHead = doc.DocumentNode.SelectSingleNode("//head");
            HtmlNode newPara = HtmlNode.CreateNode("<style>* { direction:rtl; }</style>");
            htmlHead.ChildNodes.Add(newPara);
            html = doc.DocumentNode.InnerHtml;
            IronPdf.HtmlToPdf Renderer = new IronPdf.HtmlToPdf();
            byte[] fileBytes = Renderer.RenderHtmlAsPdf(html).BinaryData;
            var fileName = string.Format(@"{0}.pdf", Guid.NewGuid());
            return File(fileBytes, System.Net.Mime.MediaTypeNames.Application.Octet, fileName);
        }