Usually, Siri captures a voice request and passes data to a server in order to respond. With an update to iOS 15, Siri will now work without internet connection. Users will be able to make specific requests via voice to control the device or execute Shortcuts.
Thanks to advancements in machine learning, starting in iOS 15, Siri will now be able to respond to users’ requests even without internet access.
Control your iPhone via Siri without internet