While Showcase doesn't have a specific built-in projection option, there are a few different ways you can share or cast your screen to present your presentation on a bigger screen in all its glory. It depends on what kind of device you're using and the other resources you have at your disposal.
We've got a whole blog post on how to project from your desktop, with a cable, or from a mobile device.
You can also cast your screen via Chromecast:
On your Android device, download the Google Home app and cast your whole screen. Make sure you've got your presentation up and running when you start casting!
Alternatively, if you want to cast from a laptop, open your presentation in our web app in a Chrome browser, click the 'More' menu (three dots in the upper right of the browser), and choose the Chromecast device that you want to use. Here are Google's step-by-step instructions.
Happy casting!