The biggest punch you can get is a tune but 1.5T tunes got hard from 2018+ when they changed the ECM. Trifecta has tunes for the 2016-2017 that get you better shifting logic and roughly 200hp but never did the 2018+. I don't think there is much you can get from part adds and swaps without a tune.
I can't speak for them as I have no experience, but another member recently suggested
Vivid Racing/VRTuned may have new tunes for the 2018+ 1.5 finally. You might check them out and inquire if that is real or not. I notice on their order page it asks what transmission and there is only one CVT so that doesn't inspire confidence but could just be generic forms. You can also
contact Trifecta and see if they have made any progress on the 2019 RS 1.5T.