Can Clara schedule internal meetings?

Yes!

If Clara has access to all calendars on a domain, or to all meeting participants' calendars, everyone will be given an email invite for the next best meeting time across everyone's calendars without email exchange. While Clara will take into account everyone's schedule, Clara will only take into account the requestor's preferences (e.g. buffer time, virtual meeting details). 

If Clara only has access to some calendars, then the meeting time will be negotiated over email.