How to upload files larger than 5mb in IIS?

I have an upload of video type files, which saves them on the server by means of an asynchrony, but at the moment that the video is larger than 5MB it does not do it for me ( It cannot be the limit since it I have assigned to 120MB ), I have located the place of the problem and it is at the moment that I assign to the variable that I have the FormData(), I leave the code of the operation:

JavaScript

//Funcion asincrona    
async function GuardarNuevoDocumento() {
    r1 = await GuardarDocumento();
    r2 = await GuardarTodo(r1);
}


function GuardarDocumento() {
  try {
    var tipo = $('#Tipo').val();
    var urlDoc = 'FuncionControlador';
    var campoDoc = 'idInput';

    
    var data = new FormData();
    var files = $("#" + campoDoc).get(0).files;
    if (files.length > 0) {
      //Si el archivo es mayor a 5 MB data continua siendo un 
      //FormData vacio, el append no lo realiza
      data.append("file", files[0]);       
    }

    var ajaxRequest = $.ajax({
      type: "POST",
      url: urlDoc,
      contentType: false,
      processData: false,
      data: data,
      success: function () {
        console.log("fin");
      },
      error: function(e){
        console.log(e);
      }
    });    
  } catch(e) {
        console.log(e)
  }
  return ajaxRequest;
}

 //ENVIAR AL CONTROLADOR
 function GuardarTodo(r1) {
   //Variables de otros inputs
   var nombre = $('#Nombre').val();
   var descripcion = $('#Descripcion').val();
   var tipo = $('#Tipo').val();
   //Declaro el archivo
   var documento = r1;

   if (documento == "") {
        //popup error
     avisos.error("Video", "El video no ha podido ser guardado");
   } else {
     //GUARDAR VIDEO(No es la función real, esta compilado de cabeza,
     //funciona bien la real)
     var data = [{"Nombre": nombre, "Descripcion":descripcion, "Tipo":tipo, "Documento": documento}]
     $.ajax({
       type: "POST",
       url: "URL",
       contentType: false,
       processData: false,
       data: data
     });    
   }
 }

C#

[HttpPost]
public ActionResult MultimediaUpload()
{
    try
    {
        var path = "";

        if (Request.Files.Count > 0)
        {
            path = PdfUpload(Request.Files[0], "RUTA");
        }

        return Content(path);
    }
    catch (Exception e)
    {
        //LOG
        _log.Error(e);
        return null;
    }
}


public string PdfUpload(HttpPostedFileBase file, string ruta)
{
    if (file != null && file.ContentLength > 0)
    {
        var fileName = Path.GetFileName(file.FileName);
        string path = Path.Combine(ruta, fileName);
        file.SaveAs(path);
        return path;
    }
    else
        return null;
}

Now having all the code present, I know that being a heavy file I need to perform some task so that the execution of the script is paused until the file is loaded into data, I have tried with:

data.append("file", files[0]).then(ajaxRequest);

and also with setTimeout, but with this one, it doesn't matter how long you put it, it executes linearly and without pausing.

How can I do it so that regardless of the size of the video I assign it?