Need help please, I'm having trouble finding resources on the internet to set up this session connection system

Hello, I am a beginner developer (Reactjs, mern...) But I remain open to learn other technologies.
I would like to develop a web application with two ways to access a user's session.
the first: the classic, the user enters his identifiers and he is recognized by the database and he can do all the manipulations he wants in his session.

And the second: without authentication, you access a user's session (from a link for example) but without having the rights to modify the elements that are displayed. We are just in visitor mode.

Can you guide me to sources that can help me achieve this?