Source: https://benmarshall.me/responsive-iframes

An iframe has fixed width and height properties. To make it full screen, add the following CSS and change the padding-top % as needed.

.iframe-container {
  overflow: hidden;
  padding-top: 56.25%;
  position: relative;
}

.iframe-container iframe {
   border: 0;
   height: 100%;
   left: 0;
   position: absolute;
   top: 0;
   width: 100%;
}Code language: CSS (css)

Then add the iframe code to the code module as follows:

<div class="iframe-container">
<iframe src="SourceUrl” frameborder="0" style="border:0" allowfullscreen>
</iframe>
</div>Code language: HTML, XML (xml)