Here are National Geographic's "Your Shot" guidelines; one could think, similar guidelines apply internally:
"YOUR SHOT PHOTO GUIDELINES
We allow and encourage all types of photography. We love to see new photography and watch our members experiment with creative styles and techniques. We are device agnostic, happy to see images from full-frame DSLRs, film cameras, smartphones, and others. Our biggest ask is that the photos stay true to your personal vision and to what you saw. Please avoid heavy-handed processing. We want to see the world through your eyes, not through the excessive use of editing tools. If the photograph is manipulated, please describe your process in the caption. Below are some basic photo guidelines.
ETHICS: National Geographic supports ethical photography that accurately represents cultures, ecosystems, and wildlife. We expect that the welfare of people, animals, and their environments take precedence over photography. In other words, don’t harm or manipulate the subject or its environment for the sake of creating an image.
CAPTION: We insist on truth in captioning and expect full disclosure in the story behind the photo. The description should be complete and accurate. Not only does this establish trust and lend greater credibility to your photo, but it also increases the engagement of the viewer.
BURNING AND DODGING: Brightening or darkening specific areas in an image is allowed but should be kept to a minimum and not done to the point where it is obvious. Your goal in using digital darkroom techniques should only be to adjust the dynamic tonal range and color balance of an image so that it more closely resembles what you saw and communicates the mood of the scene.
CROPPING: Cropping is allowed, but composing the image in-camera is always ideal.
CLONING: Cloning is not allowed.
BLACK AND WHITE PHOTOGRAPHY: Converting your color photos to black and white is acceptable.
STITCHED PANORAMAS: These are allowed only if the segments were all made within the same time frame. Don't create panoramas with sections made at significantly different times. Do not change focal length while creating a stitched image. Do not stretch the meaning of panorama to include elements that weren't in the scene as you saw it. If your photo is a stitched image, please indicate so in the caption.
COMPOSITE OR HIGH DYNAMIC RANGE (HDR): These shots are allowed only if the combined parts are made at the same time. Don't submit final images where the foreground was shot at noon and the sky at sunset. If your photo is an HDR image, please indicate this in the caption.
FILTERS: We allow filters on photographs. We ask that you please include a description of how the style was achieved and which filter or technique was used. Use discretion, however, as overprocessing can often make the photo look cartoonish.
WATERMARKS: Your Shot always credits the author of a photo whenever and wherever it appears on the site, along with providing a link to the author's profile. Because of this, there's no need to watermark your photo. A small and subtle watermark is allowed but not encouraged—we want to see your photograph without any distractions.
INAPPROPRIATE CONTENT: Any content that violates the National Geographic Terms of Service will be removed from the site. This includes inappropriate, pornographic or offensive, or otherwise objectionable content, hate speech, and copyright violations. Your assistance in notifying us of photos or profiles that may violate the Terms of Service is appreciated."
I found some additional guidelines in connection with "Instagram" type of pictures:
