Hi there,
No, there is no such option in this plugin to restrict the entire website so that only logged in users can visit. But what you can do with this plugin is, use the Content Restriction feature of this plugin to restrict page/posts contents entirely or partially depending upon your needs.
The feature is available as an add-on. You can learn more about it here: https://wpeverest.com/wordpress-plugins/user-registration/content-restriction/
Let me know if you have any other questions and I will get back to you.
Regards!
