Welcome to the forum @spdsl
First you need to add the Wyze Skill in the Alexa App and authenticate the skill to your Wyze account.
Once that is done you can create a routine in the Alexa App
If person detected then turn on the Alexa switch. Which will look something like this
Please note that you need to subscribe to cam plus lite or cam plus in order to get the person detection capability on the camera and in Alexa.
If you would like greater detail on any of the items above please let us know.