If your iPhone lacks a home button or your actual home button is not working, you can add a virtual one using AssistiveTouch.
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" ...
Next up is the action button, up on the left-hand side as you look at the iPhone, which has replaced the old ring / silent ...