Creating a full-fledged metaverse world is a complex and multidisciplinary task that typically involves expertise in various fields such as 3D modeling, game development, networking, and virtual reality.

Here is a general guide on how you might approach creating a basic metaverse world:

Conceptualize Your Metaverse: Define the overarching theme, purpose, and scope of your metaverse. Consider the type of interactions you want to enable, the target audience, and the overall user experience you want to create.
Choose the Right Tools and Technologies: Depending on your goals, choose the appropriate tools and technologies. Some commonly used technologies and frameworks for creating a metaverse include Unity, Unreal Engine, Three.js, A-Frame, and Babylon.js.
Design the 3D Environment: Use 3D modeling software like Blender, Maya, or 3ds Max to create digital assets for your metaverse, such as landscapes, buildings, avatars, and other objects.
Implement Interactivity and Gameplay: Use a game engine like Unity or Unreal Engine to bring your 3D assets to life. Add interactivity, physics, and gameplay mechanics to enable user interaction within the metaverse.
Integrate Networking and Multiplayer Functionality: Implement networking functionality to enable real-time interactions and multiplayer capabilities within your metaverse. Consider using networking libraries like Photon or Mirror if you're using Unity, or Socket.io if you're building a web-based metaverse.
Ensure Cross-Platform Compatibility: Optimize your metaverse for cross-platform compatibility to ensure that users can access it from various devices, including PCs, mobile devices, and VR headsets.

I have just shared a small piece of information, if you are looking for a end to end guide then check out the official guide:

How To Create A Metaverse