Good online venues for shared space?

Standard advice given on how to meet an INTJ is to share interests and get to know one another first. That much I understand; things like TTRPGs, psychological or philosophical reading groups and other hobbies. My question is: what are your specific recommendations online?

Are there any TTRPG websites or reading group communities that you know of that you could cite as an example?

I also have a passion for classical antiquity, which could be another in-road. Thank you so much!