load dom loaded html inside @$dom->loadHTML in php

I have explored whole google to find an answer to my scenario

I know i should declare $html content but my scenario is different: I need to get html from already loaded html in the DOM, not from php string.

<?php
  
$dom = new DOMDocument();
$html = '<script>$(document).ready(function () { $("#page_body").html();});</script>';
@$dom->loadHTML($html);
?>

Here is my html:

<td style="" id="page_body">
    <span class="classhr" style="border-top: 1px solid black;border-bottom: 1px solid black;color: red;">Routine:</span>
</td>

Even with jquery I am not able to get the html inside the loaded DOM html div.