Does Commerce have different shop designs or themes to choose from?
Commerce ships with a single default theme that is meant to be used as a starting point. It's not the prettiest, admittedly, so we do encourage you to style it more to fit your brand and design skills. Learn more about that process here.
There is one official theme currently available that brings a bit more bling, but is still by all intents and purposes meant to be customised and adapted. It's called the "Red" Starter Pack, and can be separately installed from our package provider for free. The starter pack comes with a couple more useful features like AJAX add-to-cart and checkout handling, a dynamic mini-cart in the header, as well as some basic product and catalog pages integrated with Collections and Tagger. Also has an account section.
If you're a designer and made a much-better-looking theme, we'd love to see it and help you share that with the Commerce community. The Red starter pack including its build system is also open source.