Are you sure you actually want multiple X screens? Most users just use multiple display devices on a single X screen, partly because no modern Linux desktop environment supports more than a single X screen.
That said, I think DISPLAY=redhat8:0.1 isn’t working because that syntax causes it to try to use TCP to connect to the server, and modern X servers don’t listen on TCP sockets anymore for security reasons. Please give DISPLAY=:0.1 a try: that will make it use a local UNIX socket instead that the server should actually be listening to.