UNITY_BUILD doesn't seem to propagate to dependent projects

From this line of code:
https://github.com/cpp-best-practices/cmake_template/blob/d19d8921771ba582824948f0cc57f849a5c6efd8/ProjectOptions.cmake#L147C3-L147C98
One can get the impression that linking to `myproject_options` would be sufficient to enable unity build on a project. As far as I can tell that is not correct, the UNITY_BUILD property seems to not propagate to dependent projects. Or am I missing something here?

If one doesn't want set UNITY_BUILD globally, l guess one have to set the property for each target explicitly...