They are already installed. There are two (mutually exclusive) ways to like a post/topic. One that you see here in this topic:
See the up and down arrows? That gives you the ability to “like” (up arrow) or “dislike” (down arrow) and on top of that you can also add a comment very specific to the post by clicking on the “Add a comment” link. This is IMHO the more flexible way of handling things and most Categories here have been set into this mode.
The other way is less flexible, less clear, less descriptive by adding a “like” emoji. Main drawback with that is that it is very unclear what a person means.
I personally prefer the way we have set it right now, but that can of course be changed if the majority of the powers that be decide that.
Dies ist nur Veranschaulichung, einfach ignorieren.