I found a server called Adults Night Out and it is made for players who are 18 plus. It is a chill place where adults can build and explore without dealing with kids and random chaos.
It feels like more than just a Minecraft server because people also hang out and talk while doing other stuff too. The staff keeps the server updated and they add new features a lot based on community suggestions.
Your builds are protected with CoreProtect and a custom land claiming plugin so grief and theft are not a big worry. There are daily rewards for showing up and there is Slimefun for machines and gadgets with lore.
It also has mcMMO so you can level up skills like mining swords and fishing for perks. The server runs on dedicated hardware that is managed by a sysadmin so it is built to stay smooth even with heavy features.
