Siri works differently on a Apple watch in comparison to an iPhone, here is a quick guide to getting started with Siri on your Apple Watch.
You can ask Siri to start a specific workout, open an app, send a message, and much more. There are several ways to talk to Siri. On Apple Watch Series 3 or later, Siri speaks responses to you, and you can activate and use Siri from a paired Bluetooth headset. On earlier models, Siri responds visually on your watch face.
With watchOS 6, you can ask Siri to identify a song and get an instant Shazam result. You can also ask Siri a general question and Apple Watch displays the first few search results along with a brief excerpt from each page. Just tap Open Page to view the page on Apple Watch.
With watchOS 5 and later and Apple Watch Series 3 or later, you don't need to say "Hey Siri" to get Siri's attention.
Here's how to turn the Raise To Speak feature off or on: