New in iOS 13: Swipe to Type. Swipe to Type (or Slide to type, in Apple's words) is a new way to enter text from the keyboard.
iOS 13.1.3 has a bug: you can't rearrange app icons! Well, actually you can, but you have to know the trick. Here it is.
The latest iOS version is 13.2, released Monday, October 28th, 2019. If you've already updated to iOS 13, definitely get this update (and keep up with future updates as they come along). This is the first version of iOS 13 that I can recommend. It still has some annoying behaviors but it works well.
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.