The Projects editor comes with several pre-built templates. They're great for kicking off lots of types of Projects, but if they don't fit your needs you can create your own!
Any of your Projects can be a template. To make a Project available as a template, first click "Settings" to open the Project Settings menu. Then, slide the toggle switch under "Project Description" to "Template".
Finally, save your settings by clicking the green "Save and Close" button.
After yo do that, your Project becomes available as a template. The next time you open a new Project, you'll see your template in the Project Root under "My Templates".
And don't forget, you can make Pen templates too!