Now we graduate from using pencil, and optional pen/ink work, to using a pen with a nib and Indian ink. This is a whole new world, and like any medium, takes time and effort to master.
This one is copied from Hilary Knight’s illustrations, from the book “Eloise Takes A Bawth” (by Kay Thompson).
It’s done with a pen and brush, using Indian ink.
Maybe some help from above would do it: