First, excuse my bad (very) english 
I don’t master the “nighty builds” elaboration, but it seems that the current version allows to use abstract profiles
https://github.com/Beep6581/RawTherapee/releases/tag/nightly
“Abstract profiles” in RT are different from those implemented in LCMS, they use other principles that you can see here
https://discuss.pixls.us/t/a-new-tool-in-rawtherapee-abstract-profile/25024/19
You can also see the Rawpedia documentation
https://rawpedia.rawtherapee.com/Color_Management#Abstract_profiles_.E2.80.93_16_May_2021
jacques