if you mean the proper expensine mx winter one with the boa laces normal size then your normal size should be fine – same size as all my other shoes but I dont have any specialized ones
they are meant to be worn with a normal thin cycling sock that you wear all year round
Oddly a larger sock is colder as their is no void to fill with warm air
They are really good and very warm but when they do fill with water they are a nightmare as there is no where for the water to go – this has happened a couple of time in either biblical levels of rain or due to pedalling through very deep puddles.
Really do rate them expensive though.
Mine are 4 years old and look like they will last for ever.