A full-fledged React application, is it divided into an administrative and a public part?

Question

React

Tell me, for example, I am creating a full-fledged application that has two parts, one public, available to all users, the second part is already personal, only for authorized users.
Do I need to somehow break these parts, make them different entry points.
The question is that if there is one full-fledged application, you can also see the interface of personal pages, even if you are not authorized.
I understand that the user will not receive any data, but by switching states, you can see the internal pages.
And how are such applications usually developed? Are they broken somehow, or is additional loading done when the user is authorized?
Thank you.