It’s actually not “full screen” height, they just added a lot of spacing in between each section to give the appearance of a large content area. If you view on a laptop, then it may appear that way, but on a large monitor/screen (like what I’m using) it doesn’t fill the entire screen.
So basically just add in your content (however you plan to code it) and add more padding/space on the top and bottom of each section. And of course you’d have to be familiar with CSS in order to make these customizations.