Craft 3 best way/steps to create a login client area in frontend
I don't know any plugins that do that for you since it's integrated in Craft by default. There are Registration forms as well as Login form examples and you can create Entry forms as well.

For gating content behind logins there is the requireLogin tag which will automatically redirect you to your login route and after a successful login return to the url you wanted to visit.
Not sure what else you might need since your question is really broad.

After a registration Craft will certain system messages (utilities -> systemmessages) with activation links for their account (double-opt-in). In case a user lost/forgot his/her password you can send them a new one automatically.

You can check certain config values such as loginPath or postLoginRedirects as well.