Custom Engine - Macro

Hello,
I’m finding for UE macro to seperate code for custom build engine. Is in UE something like this?

#if USING_CUSTOM_ENGINE
   //..code
#endif

A simple way to define your custom engine would be adding your define to Engine/Source/Runtime/Core/Public/Misc/Build.h. You could also modify UBT to export your define when building the engine. In both cases ensure to add some start and end comments to flag your changes that are not wrapped within your custom define.