https://www.cnet.com/news/all-of-the-smart-home-updates-apple-announced-at-wwdc-2018/

Shortcuts is a new app coming with iOS 12 that lets you create custom phrases to trigger a specific action using Siri. Tell Siri you lost your keys, and Shortcuts should automatically communicate with your Tile locator to help you find your missing stuff. This feature is supposed to work on iOS devices, Apple Watch (via WatchOS 5) and the HomePod smart speaker (something we look forward to testing out). 

The WWDC demo also included smart home Shortcuts like "Turn on fan" or "Set thermostat to 70 degrees" -- both HomeKit automations from the Home app.