Lucid Motors has released a new video just now on how to set up Amazon Alexa in your new Lucid Air. Typically, this will be done with a Lucid delivery employee during the delivery of your Lucid Air. But here is a video on how to do it yourself if it was not done or you need to do it again after a hard reset.
Lucid also has a page on how Alexa works with the Lucid Air over here.
I suspect when CarPlay and Android Auto are enabled, there is a way to define which smart assistant you want to make the default?