Currently, it is not possible to set the lifecycle phase for new contacts created in the meeting links.
However, this would save a lot of work as currently the lifecycle phase has to be assigned via workflows. This is already possible in the forms (see screenshots)
Hopefully your one gets some more upvotes so it can be implemented. Seems weird that you can set lifecycle for regular forms, but meetings (which they treat as forms in the workflow space) you can't add anything like that. Would be great to be able to add hidden fields to the meeting scheduling form too rather than only visible ones for the contact to fill in.