Please note I can not access your website as it is in “coming soon” mode and your image attachment exceeded max allowed file size.
Please provide your website access so I can help or use your web browser code inspector to determine the custom CSS you need for your theme modifications.
The theme was not tested with any shop plugin. But most likely the reason why the page is not fullwidth for you is that it tries to display a sidebar. In that case please use this custom CSS to hide the sidebar and make the page content area wider: