https://www.minetest.net/

Hmm. Having played neither Sandbox or Sasone this might not be easy.

Gary's Mod maybe. Though you cannot build the world itself.
There's a game called Build-a-world that may appeal : http://www.buildaworld.net/
I can think of other games that let you build a world like 7 Days to die , but that is less focused on world building and more focused on survival. It does have a creative mode though and you can turn off the zombies.

Also Terraria and Startopia let you manipulate worlds , but again the focus is not on the world building and more on combat.

Sorry. Best I can think of on the spot

Build a world looks interesting. Thanks for the comments and suggestions everyone.

I couldn't get into it, but you might be interested in Wurm Unlimited. Seems to be a game/builder that you either love or hate. I suspect that if you play on a traditional server, you'll hate it. If you play locally in sandbox mode, or with massive modifiers to build/skill increase, you'll potentially love it.

Bit of a learning curve to the building elements, but incredibly detailed and flexible in terms of what you can achieve.

I forgot about Wurm. Thanks that gives me a couple to check out now. I am not too worried about learning what I need to. Plantinum Arts Sandbox wasn't always straight forward, but it was fun. There is something about creating a world that is more fun to me than actually playing a game, usually.