Overwrites email-styles.php

Hi

I have custom styling which is necessary for some emails that cannot be customized within the plugin editor as they are not part of core, however, enabling this plugin overwrites those styles in my child theme. The biggest issue I’m having is changing the h1 size, I can set size in the HEADING TEXT FIELD with <h1 style=”font-size:20px;”>Password Reset</h1> which worked for the core templates but my other emails show the default 30px, how can I have all h1 headers display at 20px? I appreciate your time.

Thanks,
Vector