Most of these are probably real. I spend/spent a lot of time on a very nasty, catty cosplay website that mostly is just comprised of women calling each other ugly/fat, talking up their own cosplay work and then occasionally posting cool work and tips on makeup and how-to tutorial stuff.
I know and have done some of these types of tricks and it's not even as hard as it seems. Some of them I can tell have post-processing/photoshop on the finals but not all of them. It mostly just involves many layers, highlighting/shadow with bronzer and white/light powder and then just a ton of patient blending and usually things like false eyelashes and very careful lip lining.
Why cosplayers do it is because you're, obviously, trying to look like a fictional character. I don't get it in everyday life as its soooo time consuming. Also, in cosplay only some of the time will someone even wait to take a picture of you and good goddamn luck finding a picture of you online even if you cant walk 5 feet through the hall without getting stopped and bombarded for shots. Because of the extremely low percentage that will get posted online, it's important to have crazy insane makeup that makes your skin look perfect from any direction because chances generally are good that the only photo that ends up online is one with you making the absolute dumbest face possible (I have a really good example of this but Im at work, I will post it later). It's so common it's a generally accepted rule of cosplay. The more photos people take of you, the higher the chance the only one that goes online and not directly into a fap folder is one of you looking like awkward incarnate.
Anyway all that is to say, yeah this stuff is specifically for photographs. This method of heavy highlights and shadows is specifically made for medium-long distance glamour shots, not for getting up close in someones face in person or anything.
I don't go crazy like some of these, but I do use the same general practices