Many times I like to search just for specific movies such as "serial killer" or "true story".
I don't want to judge you, but it's creepy
I have yet seen any of these futures included in any movie database.
The IMDb does it. You just have to set the search type to "keywords". It can work with multiple keywords at the same time!https://www.imdb.com/search/keyword?keywords=serial-killer%2Cbased-on-true-story&sort=moviemeter,asc&mode=detail&page=1&ref_=kw_ref_key
You can further filter by genre, by year, by IMDb rating, etc...