You can absolutely do that. If you want to upgrade to a paid plan to get some of the features you want, then you can switch at any time through the My Products option in your account or with the help of a GoDaddy Guide. Once you upgrade your site will have all the same customizations and work that you've already put in place, just with the added features. See Website Builder plans and pricing for more info.
Start from scratch or choose from over 500 designer-made templates to make your own website. With the world’s most innovative drag and drop website builder, you can customize or change anything. Make your site come to life with video backgrounds, scroll effects and animation. With the Wix Editor, you can create your own professional website that looks stunning.