The new version of iOS and iPadOS is available today through Settings, Software Update on all compatible devices. The new update will be needed for anyone getting the new AirPods Pro, also announced today.
For iPhone 11 and 11 Pro users, this release also adds Deep Fusion, a new image processing system for the Camera app that optimizes images with detailed textures. It is automatic and will mainly come into play for indoor and medium lighting photos.
The update also brings some new Emoji characters and a switch to control whether your Siri audio is used by Apple to improve dictation. You can now enable Siri to announce messages and a new Delete option appears when you tap and hold an app icon.
You can see a complete list of updated functions here: https://support.apple.com/en-us/HT210393#132.