Rt’s neutral profile is not supposed to bring accurate colors. For that you need a camera profile (ICC or DCP).
In RT, ICC camera profile is a legacy.
Camera profile (DCP) is automatically selected if one is shipped with RT for your camera.
In other case, you can select a standard DCP from Adobe or if you are not satisfied, create one (see http://rawpedia.rawtherapee.com/How_to_create_DCP_color_profiles and https://www.ludd.ltu.se/~torger/photography/camera-profiling.html for all arcane technical details).
note: The DCP tone curve should not be selected.
Use of DCP is very simple and required to get accurate color at the beginning of processing. ( you need also white balance which is more tricky)
The display of those colors is an other story.
That is an artistic choice