I have no idea how to make the eyelashes look right with the grooming tools. The next time I try this, I might just make a geometry nodes system to put it into the basic shape for me.
As far as I can tell, you can’t even control the thickness of the hair without geometry nodes.
I only made enough node groups to be able to (sort of) follow along with the lesson (hair noise, children, and thickness).
Looking for the example you mentioned, all I found this, but it looks like it uses geometry nodes.
Although, it looks like they are using a better noise setup than I am.