Most of that volume is air, and I use vacuum bags for storage/laundry organization. My jackets only take up the volume of a few t-shirts en route. Sweaters are more difficult, because I don't want to put handknit fabric into a vacuum bag, so the times I've needed to travel with those I wear them onto the plane as normal clothing, or slung over an arm.

I don’t do the whole minimalist packing thing but my super warm down jacket from montbell fits in a tiny stuff sack and I often wear that inside of other not so warm layers to stay comfy in the winter, so it probably depends on what you’re using for warmth.