I've used folds sparingly so far because I didn't really know how to use them. Earlier today, I had to edit a really large JSON file and it was a pain to navigate so I decided I should try out folding it.
All I had to do was add set foldmethod=syntax
to my vimrc and I was off! I previously installed vim-polyglot
so it was an extra bonus that it brings in syntax files on-demand to help with folding.