Set up Siri on iPhone or iPad
Go to Settings > Siri & Search, then do any of the following:
If you want to activate Siri with your voice on iPhone or iPad: Turn on Listen for “Siri” or “Hey Siri.”
If you want to activate Siri with a button on iPhone: Turn on Press Side Button for Siri (on an iPhone with Face ID) or Press Home for Siri (on an iPhone with a Home button).
If you want to activate Siri with a button on iPad: Turn on Press Home for Siri (on an iPad with a Home button) or Press Top Button for Siri (on other iPad models).
For more information, see the Siri topics in the iPhone User Guide or in the iPad User Guide.