The latest iOS version is 13.1.2. I recommend updating to 13.1.2 if you are already on iOS 13. If you're not on 13, stay on 12.4.2 until 13.2 comes out.
Some iPhone models look a lot alike! In iOS 12 you can find out exactly which one you have, right down to Apple's part number.
Use Siri to translate from nine foreign languages into English. See the translation, and hear it also. It's as easy as "How do you say..."
Add an item to any list in Reminders just by asking Siri. If the list doesn't exist, Siri will offer to make the list for you. Super handy.
The iPhone's built-in Camera app can scan QR codes. No need to download a specialized app for that. For older systems, use the free Qrafter app.
Siri can adjust the volume for you, hands-free. Just say "Hey Siri, turn it up" or "Hey Siri, make it softer."