Revvl 4 plus not letting me set individual text sounds for contacts

Hello! I just got the Revvl 4 plus and am trying to set individual notification sounds for certain contacts and its not showing an option for that. It lets me set a ringtone for each person though.  Is there a way to set them that I’m missing or do I need to download a separate app? If so which one?  I also need to be able to send and receive messages in group messages that allows the individual sounds while separating everyone into individual message threads (like Google messages does). Thank you!