This sort of thing can get pretty involved (I know from going down this road with my other bike, an R nine T)....
Here's a good article, to get you oriented:
Lowering a Ducati Scrambler Note that the author is dealing with a 2018 model. (If my understanding is correct, the current "re-born" Scrambler is now on its 3rd iteration, and the 2018 is from the first iteration.)
To answer your question: The author of the article was able to lower her bike by about
2 inches. But, again, her bike was a 2018 and there are differences between the model years. Also, from your other thread I gather your inseam may be even less than hers...
For myself - at 5' 5" - I'm okay with just the OEM low seat (a reduction of 20mm, I believe):
96880171A - LOWERED SEAT - SCR . For my R nine T I got custom Nitron suspension through Fast Bike Industries in Hendersonville, NC, and a thinner seat from BMW, and put it all together. Last I checked, Nitron doesn't make suspension for the Scrambler, but you could try calling the people at Fast Bike, or Ducati Omaha. Fast Bike also handles Matris suspension, and Ducati Omaha might have some ideas.
But all things considered, for your size and weight and that 27" inseam... Well, you might just be better off looking at something like a Kawasaki Vulcan S, with their Ergo-Fit system. It's supposed to be a very good bike, and you'd be hard-pressed to beat that seat height, at 27.8 inches.
Hope that helps!