You can't change Siri's name, but you can specify how Siri refers to you. Create a card in the Contacts app with the name you want Siri to call you and it will use that name. You can also simply say ...

You can invoke Siri on your iPhone, iPad, or Mac computer to read almost any text that's on the screen aloud. Enable screen speaking for your mobile device in Settings and then say "Hey Siri, speak ...