I've seen those places, it's not great. some cringey shit goes down there, and unless the server's gonna require a password then it's still open to that shit and you'd be surprised how resistant the gmod community is to some things.
Gmod was the greatest thing ever, back when you were about 12 or 13. That rule still applies. It's highly autistic and low effort, making it available to everybody. Again, great if you are a kid, not so great for us. I wish gmod matured with the player base, but it is and will forever be primarily the playground of children. I'd love to have a good game platform to RP with in a relatively non-cringe way, but Gmod is not it. Patriot Anon is right too. You'd have to password it.
They called passworded servers, name the server a random collection of digits and post rhe password here