I mean, just buy them.
They're beautiful, classic, a great fabric composition. Thick, stylish, fancy. LOVE THEM.
I ordered the XXL because I am a bit of a bigger girl these days, but based on my measurements compared to the site, their currently sized XXL fits bigger than me. Based on that, I say it runs big.
In US brands, I comfortably wear a US 14 bottom (Athleta/Lululemon).