Few static pages and react for dashboard setup

I’m learning React and I would like to create site where I can have few static pages like index.html, about.html and login.html but once someone log in I would like to show them dashboard. I know I could do it easly with framework like Nextjs but how should I setup my cra to do something like this? I assume that login.html is place where I should start my react app. Standard cra sets up index.html with div element with class root but I would like to change it a little bit. What is a right way to achive it?