How are transistors actually designed

Hi, I’ve always been curious about this but never knew. I’m somewhat familiar with device physics, materials science and Tcad software, but I really cannot find good information on this anywhere. this isn’t so much a physics question but a “what do they use to make it” question. Do they just simulate it in Sentaurus or is there something else they do? I say they but I essentially mean the big players like tsmc or samsung and how they develop new process nodes. I’m also fine doing supplementary reading to understand a more complete description as I need to do so anyway. Thanks for any info!