Hi!
Currently, the event website doesn't support this OOB. However, the event website that is shipped with the product is an example website, written in Angular - and which can be extended.
Which means that you can limit visibility of certain sessions and session information - and prevent contacts from registering for them by extending the event website (based on how you're doing login for your website (Dynamics portal/ Azure). However, you would have to create an intermediate layer between the event API and your website, and only pass on the relevant information to the website (based on a contact's logged in status).
Hope this helps directionally. If you'd have more questions, please don't hesitate to ask here.
Regards,
Shravan Suri
PM, Event Management, D365 Marketing