currently no, as far as I know of, just 1 shared text chat room for the whole Roll20 game, all-Pages share it. The main, small, built-in exception is Whispering, so anyone can send a secret side whisper to a selected person (and maybe to a group of players), and that is still the shared text chat room, just hides the message from everyone except the Whisper recipient list. There is a trick way to leverage the Whisper functionality to whisher to Groups of people (by whispering to a Shared Character). Still, not nearly as powerful as what you're asking for. So a lot of people use a side app like Discord for this because you can easily do that with Discord, just unfortunately then it doesn't have the Roll20 dice roller.