Back in VP 17 days I downloaded a really nice and useful third party EQ and somehow managed to get it to come up in VP 17's audio FX list. Don't know how I did it but somehow I stumbled on success. This EQ has some features I really like and is free from 2 Sense Audio. You might check it out -- it was recommended by Alex Knickerbocker (who is a pro audio guy) in this video . It makes it easy to sweep across the frequency spectrum to find and isolate problematic sounds and has a built in spectrum analyzer. And it looks kind of cool. And it is free.
I've had no success in getting it to come up in VP18. Do you know what the procedure is?
In case it is helpful: the plug in file that comes up in my VP 17 is in C:\Program Files\Steinberg\Vst Plugins.