It's about intensity vs windchill.

For a ride where I'm toodling along, I put on a heavy coat (read ski coat).

That's rare--normally I'm working hard. I could get by with a t-shirt and $10 Walmart windbreaker + fleece facemask.

My favorite at 20-35F is a baselayer, poly not tight is fine. Then cheap windbreaker (standup collar, not hood) + poly balaclava.

At 10F, I add fleece. In all cases it's bike tights down below and snow boots or bike shoes + neoprene overshoes.

Below 10, it's not very fun but you can layer up but likely won't hit a sustainable workload as your breath is short and you'll be moving slow--so the layers just slow the inevitable chill. Give it 30 min...

That said, with my layers I expect to be cold for the first five minutes.