Include project into plugin?

Hi,

I am fairly new with Unreal and I am working with the CitySample demo in Unreal 5. I put my own c++ code into a plugin for abstraction + compile times but my plugin needs to be able to have a pointer to ACitySampleVehicleBase and be able to manipulate that. How do I tell my plugin where to find to class? Normally you would link to other plugins in the .Build.cs file but the target file is not within a plugin, it’s in the project code. Is it possible to link to that?

Best regards