How to implement a system of custom dynamic 3D models?

Question

3D

Not very knowledgeable in such matters, but the idea is as follows:
for an online 3d game, you need to implement the ability for users to add various models that must interact in a certain way (for example, transport or various mechanisms that change their behavior depending on external (game) parameters), and See also the instructions themselves for managing these models.
If you make a strict interface for transport, then you could divide it into classes in which you set certain properties and what should be there and how to work, starting from wheels and ending with door mechanisms, and take it all from custom XML and .obj , but as for me it will not be flexible enough. Indeed, it will be somehow painful to write classes for different types of objects.
Moreover, you still need to somehow allow the user to manage the existing models in the form of instructions.
The question is how to implement it? Tell me in which direction to dig or suitable literature