I would say fairly snug. I wear 2 pairs of medium thick socks to work and the boots work just fine with those. I’ve needed to grab something from the car and put my boots on while wearing some super thick fluffy winter stocks and those did not work with the boots.
I recommend Colombia with omni heat. I have an older set. It’s probably 7 years old and I could probably get another year out of them but I’d rather be prepared and get them before I need them.