Can UE4 run external C++ script created by modders that inherits from pre-compiled game classes?

So, I have this random thought when brainstorming, a modding system where, in theory, modders could inherit from pre-compiled C++ classes (DLLs) to create custom scripts (trainers, scene editor, etc.)
The question is, is it even possible for UE4 to execute external C++ script that inherits from pre-compiled game classes**?**