JSFiddle - React, Tailwind, and code Playground
HTML
<div class="content">
<h2>Lorem</h2>
<div>
<p>ipsum dolor sit amet</p>
<p>ipsum dolor sit amet</p>
<p>ipsum dolor sit amet</p>
</div>
<h2>Lorem</h2>
<div>
<p>ipsum dolor sit amet</p>
<p>ipsum dolor sit amet</p>
<p>ipsum dolor sit amet</p>
<p>ipsum dolor sit amet</p>
</div>
</div>
JavaScript
$('div.content h2').each(function() {
$(this).next('div').children('p:odd').after('<div class="clearfix">xxx</div>');
});