I found an 18+ Minecraft Java Edition SMP that is starting a brand new world with borders that people can claim.
It runs the ATM10 modpack and it is meant to be long term. The vibe is survival with politics and industry and big progression. People can make factions or nations or clans and try to build power and make alliances.
They are also working on PvP and griefing rules and letting people vote on them so fights have meaning and it does not turn into total chaos. There is also a player economy idea with shops and trading so you can try to control the market.
