Login for a multiplayer client-server game

I am working for a multiplayer game that use netCode to have some clients that interact with a server.
I need to identify players by a unique way also if players end the connection and reconnect later.

I am thinking about a sort of login used by the client. I found some ways like Unity login and Google, but I am confuded about what is the best for my case.

I think the best way to authenticate users is that they login client side and next send to server a sort of token that is checked. Is this the common way to do this?
As I said, I found some solutions, like Unity login and more than one Google tools (like this but I don't know if it is the best way https://forum.unity.com/threads/tutorial-authentication-with-google-play-games.1409151/#post-8859585).
What of these methods should I use?