How to enable and use Siri on any iPhone X model in 2 different ways

You can use Siri on an iPhone XR, iPhone XS, or iPhone X in two ways: either with the Side button, or through a "Hey Siri" voice command.
MacRumors

Assign Control Center Functions to Your iPhone's Action Button

The Action button, introduced with the iPhone 15 Pro models and now featured on all iPhone 16 models, offers users a customizable hardware button for quick access to various functions. With iOS 18, ...