Hi WilsonsWines - and welcome. I don't pretend to be an expert and those on this forum who are far more knowledgeable than I may disagree but I don't think that viscosity has very much to do with the percentage of alcohol in a liquid. Sugar may, but the sugar that adds to the viscosity is sugar that has not fermented. I think the key element is that the longer it takes a wine to slide down your throat and as it does so the more it coats your tongue and the inside of your mouth the "thicker" the wine feels. Since alcohol itself is less dense than water then I would imagine that the greater the percentage of alcohol in a liquid - all other things being equal - the less viscous that wine will feel.
Now, unfermented sugars can add to the body of a wine but some yeasts are viewed as producing glycerols (BV7, for example) and the presence of glycerols will increase mouthfeel.
I recently made a mead (orange blossom honey) with juniper berries and some spices to sorta kinda mimic a gin. It's quite delicious in my opinion, is about 9% ABV and has the greatest mouthfeel of any mead I have made to date. I fermented the honey with an ale yeast - WLP 515 which fermented the must down to .098 before I added more juniper berries to the secondary. So, bottom line: I would argue that mouthfeel has little to do with alcohol per se and very much to do with the other substances in the wine that add a thicker body - unfermented sugars, glycerols, tannins, the "density" or richness of the flavor, etc.
Edit: Just saw Richmke's post above and looks like we agree. For the record, this mead I made is not sweet (gravity is below 1.000 ) yet it tastes sweet (to me)... Perhaps because of the effects the cinnamon, the nutmeg, corriander, the liquorice and all spice have... )