I used to attend a meetup that was specifically about discussing 'big' things. This would include philosophical questions, but also things like 'discipline', 'motivation', or 'work / life balance'.

We had only two real rules. One: listen to each other and exchange viewpoints respectfully, so no (or only minimal) discussion centered around arguing or convincing the other of your viewpoint especially when the topics are sensitive (religion, for example). And two: keep things somewhat personal, and avoid purely abstract philosophical talk.

In regards to the second (often contested) rule: the personal exchange makes the conversation relevant, promotes friendship and group bonding. On top of that it makes the meetup accessible to shy people or people who are not too into abstract debates (and who, interestingly, often occupied the crucial roles of creating group cohesion and continuity!). It also avoids getting into arguments because a supposed abstract viewpoint turns out to be more personal than the parties involved thought. Those kinds of arguments happened surprisingly often when we broke the rule. Furthermore, the abstract / philosophical debates would inevitably happen after the meetup with the people who enjoyed that kind of thing, and the personal conversation greatly enriched even the abstract stuff that would come later.

I can highly recommend anyone who likes 'deep conversations' to join such a meetup or even organize one. Everyone involved in my meetup expressed how much they enjoyed, even needed this meetup in a sea of superficial social meetups and bar talk (which is also nice, just not enough for many of us).

If you happen to live in The Netherlands, hit me up!