Nope. Apple (and thus iPhones) doesn’t really support those people that want en_us, 24 hour time, and prefer Centigrade to Fahrenheit. This is basically world time and temp conventions but US English.
So, I just have to use en_uk... and subsequently get all the UK spelling corrections. Oddly enough, I’ve seen these corrections for so long that I’ve started just typing the UK way by default.