Not exactly torrent site, but archive.org is always a good place to include in searches for books.https://archive.org/details/texts
It's a very boomer solution, but sometimes typing in the name of a text (usually an academic tract) and "pdf" works, as you might find a third-world site that hosts an article for free that would normally be behind a paywall.
If you're interested in reading economics, mises.org as well as Tom Woods (https://tomwoods.com/freebooks/)
publish a lot of their books for free because they consider the message and publicity more important than sales. It's genius marketing; I don't know if Counter-Currents does the same thing but they should.
Last time i checked, good ol' piratebay.org works pretty well