@User: Extracted models are determined by what type is used for the transistor gate, with the ability to specify different variations according to the source, drain, substrate, and/or overlapping ID layer. The extraction types are in the .tech file under the "extract" section. The current extraction section for sky130A converts magic type "nfet" to model "nshort". Type "nfet" is what you get if you draw poly over ndiffusion (or ndiffusion over poly). You can get type "nlowvt" by painting magic type "nfetlvt" over the gate area (replaces "nfet").