Howard is going to get an iPhone X, but can he get an unlocked one? Leo says not yet. Apple will eventually do that, but if he buys the Verizon version, a SIM from any carrier will work because they have all the radios and Verizon is under an order from the federal government to unlock all phone's LTE SIMs. It's not exactly an unlocked phone per se, but it works like one.
He should check out iMore's article: "Here's now to buy an iPhone X that's unlocked."