[Support request] Content.php edits

Hello,
I wanted a popup plugin to cause all post detail pages to launch as popups. The plugin publisher wants a statement inserted into the contents.php file to accomplish this. But then warned that updating the theme will wipe it out. Here’s the code:

the_title( sprintf( '<h2 class="entry-title" itemprop="headline"><a class="sg-iframe-popup-133" href="%s" rel="bookmark">', esc_url( get_permalink() ) ), '</a></h2>' );

That added the sg-iframe-popup-133 statement. Is there a better way to accomplish this so I’m not at risk with theme updates?

Thanks