Hi @franmat10,
No, currently there’s no way to assign a theme to the shortcode via parameters. That’s a widget-only feature for now.
However, there’s a workaround:
1. Go to Plugins > Plugin Editor and select WordPress Popular Posts from the dropdown.
2. Click on assets > themes > [your-preferred-theme] > config.json to open this config file.
You’ll notice that this config file uses the exact same parameters that are available to the shortcode. The parameters you’re interested in are wpp_start, wpp_end and post_html. Add those to your shortcode and set them up just the same way as you see them on the json file. For example:
[wpp wpp_start="<ul class=\"wpp-list wpp-cards\">" wpp_end="</ul>" post_html="<li>{thumb_img} <div class=\"wpp-item-data\">{taxonomy} {title} <p class=\"wpp-excerpt\">{excerpt}</p></div></li>"]
3. Finally, follow these instructions.