Advanced Web Design and Dev concepts and tricks (help!)

Hi, I'm on a journey to collect all the 5 Web Design feature stones to gain enough power to one day have a project listed on awwwards.com.

I've also come to you, a humble developer... asking for help.

There's a huge gap between learning animation and page transition libraries like GSAP and BarbaJS and building come of the cool stuff showcased on awwwards.com. Stuff like interactive cursors are simple enough but even though there's nowhere I can find online for how to actually implement it in the way it's commonly used (trade secret among agencies maybe?).

However, what's pressing on my mind right now is a much more complicated one. The best way I can describe it is "persisting an element between pages" when using page transition libraries like BarbaJS.
Actually, let me just show you: https://danielebuffa.me/work. Just click on the portfolio item there and it takes the current page's image and (get ready to nut) it transitions it into the next page.

This is the stuff of legends.

And... I can't quite figure it out.

So I'm asking the old masters in the community here to help me reverse engineer it and explain the implementation a bit.

What are your favourite hot web design and dev tricks and concepts that make your friends wonder if you have a website fetish? I'd love to discuss.