JSFiddle - React, Tailwind, and code Playground

HTML

<h3>2342</h3>
<p>dfgdfg</p>
<p>dfgdf</p>
<p>dfgdfgdfg</p>
<h3>2342</h3>
<p>dfgdfg</p>
<p>dfgdf</p>
<p>dfgdfgdfg</p>
<h3>2342</h3>
<p>dfgdfg</p>
<p>dfgdf</p>
<p>dfgdfgdfg</p>
<h3>2342</h3>
<p>dfgdfg</p>
<p>dfgdf</p>
<p>dfgdfgdfg</p>

CSS

.content {color: red;}

JavaScript

$('h3').each(function() {
  $(this).nextUntil('h3').wrapAll('<div class="content"></div>');
});