Basesd on my own experience and my extensive boot collection,
these boots do run true to size. I will add, as I don't care for a tight fitting boot, I ALWAYS buy at least 1/2 size larger cowboy boots than any other kind of shoe. This allows for whatever socks I wear and my feet swelling (which everyones feet do). If they feel too big with the thickest socks on or if they fit fine with thick socks but you want to wear a thin sock, put a foam insole in them. Cowboy boots do not fit like any other shoe either, so with your first pair, you may think they don't fit because your heel slips. It will always slip in cowboy boots. I suggest wearing them inside the house all day while you get used to them.