How to change type of Heading in Accordion

Hi,

Thanks for contacting us.

The plugin used at your end is WPBakery Page Builder: https://wpbakery.com/
The Visual Composer Website Builder: https://visualcomposer.com/ and WPBakery Page Builder are two independent products.
You can find more info here: https://visualcomposer.com/docs/faq/visual-composer-website-builder-vs-wpbakery-page-builder/
As your question is related to WPBakery Page Builder plugin, we would request you to open a ticket via it’s support portal: https://support.wpbakery.com/ so that the support team can guide you with it.