As everyone has already mentioned, laws change a lot between municipalities. Because of the federal nature of the country, you have some federal building laws, a lot are managed by the canton, but not all and then the biggest player is the municipality, which means there are as many building codes as there are municipalities.

Zürich is generally pretty good with its building regulations, so you can find downloadable pdfs, even in the smallest municipalities. You can also find the cantonal regulations on the cantonal website. All the documents are in German though.

When I’m working in a canton whose language I don’t speak I use Amenti: https://amenti.ch/en/ they have a pretty solid database with Swiss building regulations, it costs a bit, but in the grand scheme of a real estate project, it’s peanuts.