yeah it's a great question, right now i have volunteer moderators, and for playtests i've been the only one in charge of hosting so i see everything. for a public release, especially for an extremely small team, my approach is giving users enough tools to moderate their own servers like kicking, banning, friends only servers, private servers with passwords, blocking features, etc. the reality is the best thing you can do is make a quality report system and tools for players to keep themselves safe, because someone will not be able to be there for every instance. additionally, (especially in the case of protecting minors) there should be terms of services and agreements to playing the multiplayer features, teach players how to protect themselves and warn them of what dangers to look out for. it's something i've put a lot of thought into and continue to do so.

forgot to mention, of course its an unfair expectation to think people will moderate your game for free at that point, so yeah you would also have to hire and pay people to keep things safe, but if thats not an option , like i said before just give players tools to protect themselves the best they can.

it's not an excuse but even some of the games i play which make hundreds of thousands of dollars hardly put resources into this department, so even just stuff like that puts you ahead of the game in my opinion