Think the SE's front camera is from the 5, the aperture is listed as 2.4 (thus worse) and the 5S and higher had ones with 2.2.
There's some misinformation out there on the internet, it seems. GSMArena, for instance, lists the iPhone 5S as having a f/2.2 aperture on the front camera, and of course, it's the first Google result for "iphone 5s specs".
However, Apple's own spec sheet lists it as f/2.4, and Anandtech's review agrees.