Yes, but the screen filtering works in a different way. I don't know how to describe it but the text is better readable while the brightness is lower. If you would take a screenshot, you wouldn't see the dark filter on top of the picture which you always have with all the other screen filtering apps but just the original screenshot without any filters.
Twilight, Night mode, ... they all use a filter on top of the screen which makes everything harder to read (that's why they require the permission popup window'). F.lux 'injects' its filtering so that the screen doesn't hurt your eyes anymore and as a result of this technique you can still read text pretty good .