That sounds more like grimdark to me. There certainly some noir stories even before the 50s were protagonist can’t win, it’s not a required part of the genre. And with those, you can say they shouldn’t have become involved in a murder plot in the first place. But, whilst noir stories have lots of twists and moral greyness*, the protagonist can certainly win sometimes. Of course, the protagonist may not be “good”. There are a bunch of Harlan Coburn (and similar) thrillers on Netflix at the moment. They are noir.
*Phillip Marlowe is sometimes described as a tarnished paladin. The one good man in a world full of bad people. Sam Spade on the other hand has a moral code similar to Conan’s.