How can I change the css for the template types? e.g. I want to increase the font of the section type
By specifying the template type you are essentially assigning a CSS class class with the corresponding name (i.e. type: "section" assigns the webix_section class). This means that you can refer to the specified class and style the content as you wish: https://snippet.webix.com/nc2hadmk. Please note that you should add an extra CSS class via the css property for extra specificity (if you want to use different styles with the same type).
It looks like you're new here. If you want to get involved, click one of these buttons!