Almost any free site for downloading films is going to be
(a) illegal ; and
(b) probably packed with malware (or, at least, with lots of ads).
There are a few exceptions though, such as those listed here
https://www.digitaltrends.com/movies/where-to-watch-free-movies-online/
The British Film Institute also has loads of films available for free. They're mainly documentaries but there are a few feature films included as well:
https://player.bfi.org.uk/free/collections
Don't expect to find any legal sites hosting major feature films for free though!