Help with getting into trait portrait modifier modding

[BananaPikachu]

Hi, I was wondering if I could get help with getting started with modding in ck3.

Was thinking about starting with something simpe to start with and thought for my first project would be a femboy/mascgirl trait that just clanges character models used so male characters use the female character model and vice versa.

Anyone willing to give me a bit of help nudging me in the right direction to understand what to do? I know a tiny bit about modding from ck2 but that was mostly to read event triggers.