There are two major questions.

1. How can I render partial view on change event of Html. dropdownlist? And It should be noted that RenderPartial should be called in specified div having class="row mt-3". I want to do this on change event of Dropdown list by not disturbing the html position of partial view. Html.RenderPartial("GalleryListing")

Current HTML Code

<div class="col text-center">
            <div class="section_title new_arrivals_title">
                <h2>Completed Projects</h2>
                    @Html.DropDownList("GalleryFilter", new List<SelectListItem>  
                      {  
                        new SelectListItem{ Text="Exterior Signage", Value = "Exterior Signage" },  
                        new SelectListItem{ Text="Interior Signage", Value = "Interior Signage" }
                       },"Please Select Category",new { @onChange =""}) 
            </div>
        </div>
    </div>
    <div class="row mt-3">
       @{Html.RenderPartial("GalleryListing");}
    </div>

1. I need to pass the selected value of an HTML.dropdownlist to a partial view file in Umbraco. Kindly note that there is no controller in Umbraco so I cannot send value through ajax request etc. I have to do it by remaining in Razor view. I don't know if it could be done in onChange event? The main issue is to pass this value into PartialView.cshtml which is being rendered by RenderPartial event. Current Dropdownlist

   @Html.DropDownList("GalleryFilter", new List