How can i get clickid for pixel tracking i create one but showing null

Shopify Discussion
1 
{% if order %}
  <img src="https://utils.follow.whistle.mobi/pixel.php?linkid={{ request.query_parameters['click_id'] }}&transaction_id={{ order.id }}&revenue={{ subtotal_price | money_without_currency }}&goal_name=default" width="1" height="1" />
{% endif %}

I use this code in theme.liquid all values are pass but linkid = null showing on network how can i pass and get the clickid of user

on checkout additional script i use this code

<script type="text/javascript">
function prepareFrame() {
  var linkid = "{{ request.query_parameters['click_id'] }}";
  var orderId = "{{ order.id }}";
  var transaction_id = orderId;
  var revenue = "{{ subtotal_price | money_without_currency }}"; // Use the subtotal price instead of the total price
  var url = "https://utils.follow.whistle.mobi/pixel.php?linkid=" + linkid + "&transaction_id=" + transaction_id + "&revenue=" + revenue + "&goal_name=default";
  console.log(url); // log the tracking pixel URL to the browser console
  var ifrm = document.createElement("iframe");
  ifrm.setAttribute("src", url);
  ifrm.width = "1";
  ifrm.height = "1";
  ifrm.id = "pixelcodeurl";
  document.body.appendChild(ifrm);
};
prepareFrame();
</script>

All other values are showing when i place an order but clickid or linkid showing null