I've been tasked with creating a custom WP theme for my company's website. I know PHP and decent WP plugin development but haven't worked with themes before. I'm using Underscore as a base for my theme and have written styles for header, footer etc.
Now my boss wants that the theme have support for different layouts kind of like what you see in premium themes. And the users can go in theme settings then choose the layout they want. I've searched around but found nothing on this. So, my question is using Underscore how do I go about doing something like this?