" ... slight light-brown-ish look in skin tones and in most other colours, ..."
is either a function of the light source used and/or in camera white balance settings and filtering and/or post processing.
" ... slow fade to dark in the silhouettes of the subjects and the almost zero quantity of light the camera is picking up from the background (unless it's bright, like buttons and panels).
is (probably) achieved by having camera and subject light source close to the camera and at high level so that they swamp the ambient light.
To achieve the exposure effect set the camera up as follows:
Light source close to subjects.
Small aperture (f/16 - f/22 range usually)
Camera close to subjects physically.
Adjust basic levels afterwards to maximise effect - no editing per se.
Using a flash with the above settings produces similar effects to these. See below re colour temperature.
The background drop-out occurs because the light level from the closeup lighting is high compared to the ambient light level so that when the camera exposes for the closeup source it reduces sensitivity (higher shutter speed in aperture and ISO controlled mode) so that light levels from ambient light have minimal effect.
The low apparent colour temperature here may have been achieved with a flash and unusual colour balance settings, but more likely either an LED or tungsten videolamp or fixed lighting was used. The degree of 'shine' on the faces from reflection suggests a smallish source rather than a highly diffuse one.
I believe that these two images were produced essentially as above. A very dark background may have been filled but pushing the levels up on these two pictures suggests that they have not been manipulated in that way. The fountain photo has quite a few very low level highlights which can be seen by eg massively increasing gamma - it was taken in bright daylight. The image of the young woman and child has substantial background detail but it is well down in exposure compared to the foreground. This was taken in a shop lit at normal levels by fluorescent lighting. Larger
Image at right shows that background detail is present at low level.