Siri cannot be downloaded separately
Siri is built into Apple devices and the iOS, iPadOS, macOS, watchOS, and tvOS operating systems
To use Siri, update your Apple device to the latest compatible operating system
On iPhone or iPad, go to Settings, then Siri & Search, and turn on Siri
On Mac, go to System Settings, then Siri & Spotlight, and turn on Siri
On Apple Watch, Siri is available through the paired iPhone and watch settings
On Apple TV, Siri is available in supported regions and models
If Siri is not available on your device, check device compatibility and region settings
If you want a voice assistant on non-Apple devices, install a different assistant app from the app store or device store