Does it come with flattening modules and being able to merge/patch resources or child module's resources? I fiddled with the idea of recreating this with terra

Does it come with flattening modules and being able to merge/patch resources or child module's resources? I fiddled with the idea of recreating this with terranix, but kind of lost interest after license changes. The basic motivation is to adjust/extend 3rd party modules without forking them.