if you're looking for actual published books/novels they're a lot harder to find due to strict copyright issues unless they were published a long time ago or are in school curriculums, such as books we study in english class like to kill a mockingbird, of mice and men, shakespeare, etc
you can try searching up "[book name] pdf online free" it works usually
ao3 is a fanfiction oriented website but sometimes i even find myself reading fanfiction of things i'm not even a fan of or know because some of the work written on there is comparable to actual published work, some are even better in my opinion. ao3 has way more professional work than wattpad because i think you actually have to apply for an account to write work, so it's much better and easier to find good work
is there a website where I can read books like mangago? (づ ̄ ³ ̄)づ