Want to iframe a smal part of a page for another page on the same site

Hi, I’m slow and not very good at coding, but I do know enough HTML to identify the section of page I want to put in an iframe. It’s enclosed in <div>…</div> and requires a plugin or header code to work.
I want to display the div on a different page on the same site. I want to lazy load the iframe that contains the div by using WP Rocket.
So, hope that’s clear!
I’m just looking for a clear step-by-step tutorial on how to do that using the free or paid version.
Thanks!