i took a break from rp for several years and coming back was an adjustment, but from what i'm experienced the best way to develop group dynamics is through group customs, so everyone can interact together and jump in when they want, or through group chats on wire, discord, etc. you can also use outside websites like rabbit to watch shows together, or play games on pretend you're xyzzy or board game online, etc., where everyone can interact together while doing an activity. it definitely creates an opportunity to see how character's personalities work together while doing some kind of activity.