Law libraries. You can find one near you, there are self-help type books for individuals as well as, usually, thick stacks of case law like you're seeing in this photo. Although most of those stacks are now digital. I work in a university, and my office happens to be in the law library, which is also our county law library, so is open to the public. People do spend days and weeks researching and compiling paperwork. Some people also jerk off in the stairwells, because, public library. It's boring and interesting at the same time.

The internet is going to be your best resources as most laws are available on their respective websites. From your town/state ordinances to your federal laws. Most will be online.

Where I live you can get the complete RCW for the state at the local public library (or online) but at the federal level it's insanely more complicated and changing all the time. Gotta make sure there's plenty of loopholes for rich people to exploit.

We don't even know how many laws there are

I mean, it's literally why law school is a thing, and why it's notoriously difficult and a ton of work

here in austria they're publicly available on the internet. ris.bka.gv.at i think is the website (RIS stands for "rechts-informations-system" - law information system)

a lot of the laws are actually written in a language that is somewhat easy to understand (you still have to read it carefully and a couple of times but it is comprehensible - you just gotta take the time to actually try to understand what it says)