I purchased one of these ESP32 dev kits too. It is the Waveshare ESP32-S3-ETH model and I can't seem to get the RGB led to do anything. I have tried to cycle through all of the GPIO pins with HIGH and LOW and also using the RGB_BUILTIN var but to no avail.
What I have come up with that did turn it on and I think in just green was when trying to setup the use of an AHT20 temperature/humidity sensor. For some reason it turns on and stays on. I am thinking there is something in the AHT library that operates it but I can't seem to figure out what. I have been through all the examples I can find so far with no useful results.
I have also had a heck of a time going the other way trying micropython and VSCode to program it and also Thonny. I later discovered that if your version of ESP-IDF does not line up with your version of micropython, you will run into issues compiling the ESP32 port of micropython. Option tweo was to download the bin file from micropython website but this does not have the functionality for network I will need in the final project.
Anywho, I really want something to work on this board. It has been a struggle all the way along so far.
Any ideas would be great!