Can I Control The Developers Access to Code Classes?

Hello dear community !

I'm trying to learn how to manage the code in D365 FO.

Usually, the developers have a copy of the model so he can access the classes and work on the customization.

I want the developer to do his task without having a copy of the whole model code.

How to manage this?

Is there a tool or a way to do this?

I want to learn how to manage the models, the code and accessibility.

Any advice is appreciated !

Thanks in advance ! :)