I found a Minecraft anarchy server called MinecraftOffline that runs on 1.21.11 and it is all about doing what you want.
The world is eternal and they say it never resets so your builds and mistakes stay forever. Gameplay is enhanced with bespoke plugins so it is not just plain vanilla.
It is hosted in Finland which should feel good for European players and it is built on reliable hardware so it should stay stable when you are trying to survive the chaos.
