Hi Ad7am,
I successfully managed to implement GSAP animations on the client's site. You can see the animations here: 20neLabs site.
It takes a good knowledge of JavaScript to implement these features
It would be WAY easier to implement these features if working with a Squarespace 7.0 or legacy project as you can clone the site's code to your local environment and stage changes more quickly
Working on the Squarespace environment will involve considerable time spent debugging as you have to go back and forth on styles, scripts, etc...
Your site's full wireframe must be set and done before you begin to work; this is due to Squarespace programatically adding `ids` and `classes` to elements in the DOM, all of which you cannot modify
I've attached a couple of images so you can see what I mean by injecting the scripts and so on.
The first image shows the GSAP library being injected in the document's <head> globally; this is done through the site's dashboard Settings -> Advanced -> Code Injection; the second image is of page-specific code injection in the <head> tag (meaning it will only inject the code in that specific page's <head> tag). Here you can reference elements from the page and add custom scripting code, external references, etc... To access this you click on the page's Settings -> Advanced panel and add your code there.
I hope it helps.