I think you can just use window.onscroll and in your callback just crated steps for document.body.scrollTop and if scrollTop hit those steps you can animate different elements on your website. I guess it sounds easier than it really is. The whole website needs to fixed though and you need to take control of the scroll.

But when it comes to library you can use something like https://scrollmagic.io/ or https://scrollrevealjs.org/

I’m trying to recreate some website to learn new things. I try to make something like that : https://www.wokine.com/en/, On scroll,
even a little scroll, start a complete animation.

I found some library like Sal.js or AOS.js but this actually create animation during all the scroll.

Any clue ? There is a library, a specific langage?