Hello.
Most game engines have a scene (world) file format and a scene (world) editor which can create such files.
Panda3D doesn’t have an official scene editor.
However, since the 3d model format of Panda supports so much, you can use any 3d modeller which can export Panda’s 3d model format and tag objects in it, and then in your code check each loaded model’s tag list and add logic to it like physics, your AI code, etc. based on its tags.
Example: Using tags
This might a bit confusing for newbies and the manual doesn’t do any justice when it comes to how to create scenes. So if you didn’t get something or have more questions, ask.
There are also unofficial scene editors which do all the above “under the hood” by giving you a tool to create your scenes then a Python function to load the scene file.
github.com/Derfies/panda3d-editor
(Panda really needs an official scene editor, it’s been like what, 5 years?)