Hello,
In general, you can adjust those buttons via Theme Settings -> Styles and colors -> Buttons.
https://gyazo.com/f8247d7ade8737dd34a9bb0e9b031058
ACCENT BUTTONS. Buttons that are directly related to the WooCommerce purchase functionality.
DEFAULT BUTTONS. All others, such as WooCommerce, supported plugins, and theme options buttons that are not included in the above category, and those buttons that do not have their own button settings.
For the advanced button styles, please follow this guide: https://xtemos.com/docs-topic/advanced-button-styles/
Best Regards,