No, it only goes down to the resolution of an entire world tile (because the map editor Toady programmed, which perfectworld is just a wrapper for, only goes down to world tiles).
So the entire screen full of embark tiles you have to choose from, for example, all starts out at the beginning of world gen as basically ONE elevation, that then gets a bit of local variation per embark tile that you can't directly control, then just gets eroded down. This leads to either (depending on erosion):
*A boringly gently rolling landscape, OR
*A crazy jagged, obviously glitchy computer generated mess where there are perfect rectangles everywhere, etc.
There isn't really an in between. By the time it stops looking computer generated, it's already very gently rolling.
Also, nothing about those tools allows you to encourage cliffs (other than un-eroded dumb looking square tile cliffs) and nothing makes overhangs possible (even though the existence of caverns tells us the engine is capable of understanding overhangs and storing them in memory), etc.
In other words: Perfectworld gives you a pretty world map, but accomplishes almost nothing in giving you actual embark sites you want. Aside from minorly upping your chances of finding something randomly you like. No real control.
Either it needs a method of specifying a much finer grained resolution of elevation data at the start of worldgen (embark tiles at the very least, ideally finer), or modding a site after embarking could work too, though probably more effort to make the grass and stuff all work out. Also, soil and rock layers are weirdly hard to change at that point.
Both are potentially scriptable AFAIK.