The stock Camera app doesn't allow for almost anything manual AND this is a huge problem with it, as
- there's no way to, say, force it to use high shutter speeds to shoot action in low light, even on the expense of using high sensitivities
- Apple doesn't allow third-party apps to use HDR (and panorama - nevertheless, manual settinsg don't affect pano), which is a HUGE problem as it's always preferable to use the HDR mode, Apple's implementation being THAT great.
CameraTweak has always allowed to fix these things. I haven't installed the new version of it yet as I've gone for the Note4 instead of the iPhone6+ but I'll report on it when I have the time, just like with the previous versions, of which I've written several articles.