They do: Borg (Google's internal orchestration system) is very, very flag-driven and it's commonplace for services to have hundreds or thousands. That's presumably how Chromium ended up the same way.
Yes, everything internally has many flags (hundreds or thousands), so much so that they raise the command line size limit (ARG_MAX) in the kernel. I think it was around 2GB when I left. The internal frameworks really encourage using flags too, there's a @Flag decorator for Java that's sprinkled all over the code and sometimes nested extremely deeply down chains of classes that promote this behavior (abseil, (https://abseil.io/docs/cpp/guides/flags) has macros for this too).