Levi's is probably the best for cold since the cotton is very heavy and thick, although it's obviously not going to beat wool.
Used to wear Levi's. Now their too restrictive. Although they are long lasting if they have no flaws in them, as in places where seams unravel or actual places in the fabric that have been damaged in manufacturing. There is heavy denim that's lined with another layer inside, usually of short shorn fleece (synthetic) worn by people who work outside in the winter. On occasion you can find jeans with cotton or wool lining. With jeans the problem with cold weather is that the jeans freeze, and become stiff and difficult to walk in. Prefer looser light weight wool pants with a lining, and not too itchy. Although jeans can be augmented with a long wool coat and boots as the external layer as long as you are not outside for long.
As for -30 C, at that point I'd be more worried about my face and legs than my body. Turtle neck + v-neck + hoodie + good coat. 2 heavy layers of knits will easily keep you warm. Big thick scarf that can cover the lower half and thick The coldness comes from losing heat in the face and head. If you have a down coat it's not the body that's the problem.
As long as it's not blowing snow and you're not in the open without a windbreak it's not as much of a problem. It's actually the feet, hands and face. Boots made from recycled tires with heavy wool inserts and light cotton sock liners under wool socks will just about keep your feet warm but not quite. Liners for gloves too.
Dislike scarves, feel as if I'm being strangled. Maybe it's a female difficulty as well. As someone could easily grab it. Usually it's cotton or wool underneath and a turtleneck and then coat or jacket. Most people who live in this climate have known about layering all of their lives.
As for the long down jacket, it's the best thing for the coldest weather. My grandfather wore it all of his life, then my uncle, now me. It has a really well-designed hood with a flap made of wool felt so the face is little exposed, many pockets, two slash pockets in the upper part for your hands, several internal and outside pockets. For the coldest weather it's all I'll ever need. And if it's so cold that the nose and fingertips are affected, there is a wool balaclava, that is sometimes used and snowmobile gloves.
Most of this heavy winter outerwear is wiped down, the wool hand-washed so there's no issue with micro-plastics in freshwater. Yet, most people are simply unaware of the fact that freshwater fish are now swallowing micro-plastic, and we are eating it, drinking it. I'm noticing animal behavior around the world, whales dying, sharks and raptors and bears taking fish from anglers and commercial fishing operations. It's telling and it's ominous.