How do I create a portpolio page like this in WordPress?

I want to create a portfolio page exactly like they have done it with their projects on the website [see below] where I can select the different pages of the project at the top and then scroll to the view the screenshot.

My understanding is that they have custom coded it, but how can this be achieved in WordPress using Divi? Is the only way to hire someone to custom code it and then just implement the code?

Thanks.

The page I need help with: [log in to see the link]