When I started working on a large legacy C++ code base in the early 2010s, I learnt. It took probably close to a year until I was proficient enough that I didn't regularly need to ask where to fins things. This is a skill we used to have (and some of us still have).

Though if your code base is all a vibe coded mess and you don't have a senior human colleague to ask... Good luck?

Yeah giving up is totally a viable choice, but it isn't the only option.