View selection and submit to model

Unable to display checkbox selection and submit to model for processing. Somebody can advise me, , I'm a beginner.

I tried to use JS for client-side display, but then I don't know how to send the checkbox value as true, for processing in the model:

public class IndexModel : PageModel
    {
        [BindProperty(SupportsGet = true)]
        public bool IsChecked { get; set; }
        public IndexModel()
        {
            if (IsChecked == true)
            {
                 any action... 
            }
            else
            {
                 any action...
            }
        }

I use the script

     @{
   String textName = "textName" + item.kod;
   String chBName = "myCheck" + item.kod;
   String fceName = "myFce" + item.kod + "()
  }

<script type="text/javascript">
     function @fceName {
     // Get the checkbox
     var checkBox = document.getElementById("@chBName");
     // Get the output text
     var text = document.getElementById("@textName");
     // If the checkbox is checked, display the output text
       if (checkBox.checked == true) {
         text.style.display = "block";
       } else {
       text.style.display = "none";
       }
     }
  </script>

even though I wrote, always FALSE

@Html.CheckBoxFor(model => model.IsChecked, new { @IsChecked = "true" , onclick = "@fceName" }

This is works and displays Compare, but I don't know how to send it to the model - get IsChecked is true

<input name="IsChecked" type="checkbox" value="true" id="@chBName" onclick="@fceName">