Are you looking for a free download of Adobe After-Effects? There is a very high likelihood that you made it to this page from a google search.
At the end of May 2021, I have released Colors for After-Effects, which lets you do magnificent things with colors that are not yet possible natively. It is a color sampler that lets you sample raster images (any frame from an active comp) into a compact palette. It also lets you generate new palettes on spot without thinking about it too much, so you can quickly be inspired by many different color options and start using the one you like the most. It also lets you recolor entire comps in a breeze, as well as examine and create different gradients. It also (yes a lot of alsos) lets you drop into the comp a variety of custom elements that use colors that are based on the active palette. It also does a lot more.
Here in this little space of mine, I’ll share more about the creation process of this tool.
When learning how to use After effects should you learn how to use expressions? Well, I think the main question should be: Why would you even want to?