Can I add a link styled as a button to the rich text editor?

The link can be edited via the source code to include the corresponding div class to apply the theme styles

From the rich text editor, open the source code, then add this code to configure a link as a button:

<div class="pwr-cta pwr-cta--primary-solid">

<a class="cta_button" href="#" rel="nofollow" target="_blank" rel="noopener" 
title="Button">Button Title here</a>                    

</div>

Modify the code as follows:

1. replace the # between the single quotes with your URL
2. decide whether you need to keep the nofollow and noopener attributes (if you're linking to your own website pages, it's best to remove these for SEO purposes)
3. replace Button Title here with your desired button/link text
4. change the div class to match the button style you want to use

This code will add the primary solid style from your theme settings.