I went to Palermo, Catania, Ragusa and Noto solo a few months ago. I wore extremely plain clothes (khaki pants and plain black sweater, for example) and Doc Martens boots. Since I was alone, I was hoping to be unnoticed, but I was easily picked out as American.
I did write about my experience traveling solo in Sicily in the trip report section if you want to read it, but I can tell you from successfully blending in on previous Italy trips and from being in Sicily recently, you might see strappy sandals or wedge sandals at night, but in general, women weren't toddling around on heels. People in Sicily also seem to think anything under 65F is cold weather, so they wear sweaters and scarves and blazers if there's even a little chill. Flowy, printed items seemed to be popular for tops and dresses. Flowy pleated dress pants and cropped tops (not so much showing midriff, just meeting the pants) on the younger set and fitted bright suit style pants and scarves on the older set. There were some longer high waisted skirts with slits and fitted cropped tops as well.,
On previous trips I wore things like high waisted pants with thin sweaters (not me in the photo, lol) or patterned button ups, a shorter skirt with tights and a thin ribbed turtleneck, distressed cropped straight leg jeans with a white tank top and a super lightweight casual blazer, a long spaghetti strap dress with a lightweight fitted shirt underneath, and a remix of all those items (like putting the dress with the blazer, etc...). I don't know how much of it is my Roman profile, but I noticed that, when we ordered food or walked around, people tended to speak to me and my teenagers in Italian first even if they spoke to those around us in English first.
We were clocked as American more than once, of course, but my favorite was when I only said a few words of Italian to catch a taxi and the driver chatted away to me the whole way up a mountain. I understood just enough of what he said to follow until I missed something and had to ask him to repeat because I really only speak English. He let out the most disappointed groan and said, "Eeeggghh, English!" and stopped talking to me entirely! My daughters were cracking up.