You can extract 'some' tenuous info out of factory photos, but only if you know exactly what a cheap digital camera set to fully automatic does exactly when shooting a photo. It's not about lighting, it's about a camera user expecting a camera with no brains to figure out what it's supposed to be photographing without giving it any info.
For example, leftmost 'tan' has a window directly behind the doll. The bright light of the window hits the sensor, the automatic exposure algorithm thinks "oh, so many photocells are reporting 100% overdrive there, I must turn my light sensitivity down until they're some variety in that area!" and hence turn the entire image including the doll's skin darker just to get some detail on that windowframe.
In the rightmost 'tan' shot, the entire doll's body is shaded, and all the objects in the background are white and illuminated. Again, the camera that has no clue what it's photographing and wasn't told shit by its user goes "oh, I can't overexpose all those bright areas in my picture (the background, of which it doesn't know that it's background), I must extract all the detail out of that brightness!" and turns its light sensitivity down a lot, making the doll darker.
Only in the middle 'Tan' image is the dolls skina ctually directly lit, and the camera has some information on what is bright (the place she's sitting on), and it has some area that tell it what is black (her hair). It is the only photo of the three that even has a chance of a camera on automatic getting exposure even only in the ballpark of realistic.
Then there's color temperature and/or tint, which a camera on auto can only set right if there are many different colors in the image, so that it has any information within the picture of what colors it is actually seeing. There aren't many diverse colors on those images, leading to some images being very warm (orange tint), and some being very cold (blue tint). That tint can easily change a tan skin color into pink, which makes it extra confusing for factories actually offering a pink skin tone. You can be happy that 6ye only offer 4 tones, since with Jinsan's 7 skin tones, the chaos is /insufferable/. It's the reason I didn't get a WM. I had no clue whatsoever what I'd be getting.
Even with a lot of experience, most of these photos do not remotely contain enough information in the picture for even a human to correct them in post, so a dumb camera CPU would have absolutely no means to get it right in first place.
You can most reliably find out what the skin colors actually are if the factory you're ordering with has very consistent and professional product photography showing the same skin tones in consistently the same color on all photoshoots - a discipline in which 6ye unfortunately also isn't very good at, but they're also not the worst offender
- or you can try to find photos by users that either contain a lot of colorful reference objects of varying brightness next to the doll in all kinds of colors and white and black that look correctly lit, such as this:
... or photos for which someone did exposure and white-balance with an 18% greycard (costs 10$. It's a card. Which is grey. Single-handedly solves all issues with light and color in photography.). You can see that on this one:
(This 10$ greycard is also the secret weapon by which product photographers can produce consistent skin tones across all their shoots regardless of lighting, hence why you can judge whether one of these was used by looking at the consistency of their product photos - if they're consistent, they're having a pro product photographer and most images will be representative of what you get, if not, they're having a crap product photographer and all their images are unreliable at best, misleading at worst. Factory images are taken by workers with smartphones and are hence all unreliable by default.)
Since HR (the brand of the doll on these picures) are made in 6YE's factory and using their TPE and the same color names, it is plausible that they also simply are the same skin tones, and these shots might also be representative of what 6YE's 'natural' looks like.
Another way to get a much better idea would be to find a vendor in your region (is a person who has a skin tone you know and can identify) who has all of 6YE's dolls and makes a professional video with himself in it as a skin tone reference. Here's one of a german WM-doll vendor:
https://www.dollpark.com/mediathek/doll ... uppen.html
unfortunately, I have found no TDF-approved vendor during my research doing anything remotely like this to help their customers, nor have I found anyone doing this for 6YE dolls.