Hello @mktnegocios,
Thank you for your inquiry. The Side Menu you are referring to is actually not a Menu, but a widget that can be set from Appearance >> Widgets >> Shop Sidebar.
Unfortunately, there is no option in our theme to style it, but it will take on the default style of the widget. If you would like to style it, you will need to use Custom CSS. You can refer to this website to understand how to pick the selector and apply the style using Custom CSS: https://www.w3schools.com/css/css_selectors.asp
We hope this information is helpful.
Best Regards,
8Theme’s Team