cmake --install and passing -j arg

The following command works in 3.20:
cmake --install . -prefix <path> -- -j8
but in 3.30 it results in:
Unknown argument --

The documentation for the cmake --install command in both 3.20 and the latest 3.30 don’t say that -- is supported; though it is for the --build command. I assume it was either working as undocumented behavior in 3.20 or was being silently ignored.
This issue said that -j or --parallel option is available for --install which would be an alternative the for specific case of wanting to pass -j but that doesn’t seem to be true and there is nothing present in the documentation for this either.

Is there a way to run the equivalent of [make|ninja] install -j8 through the cmake --install command so it isn’t generator dependent? Whilst following the make convention of:

Running ‘make install’ with a different value of prefix from the one used to build the program should not recompile the program.