How is Sentinel 2 MSI Natural Colours Profile in SNAP calculated

Using the ESA Toolbox named SNAP one can load a sentinel 2 data package and see a RGB view using the profile.

I am wondering what this profile in mathematical terms are.

Is it just information about which bands to use? Is it a weighting of the bands? Is it static across time/geo position?

How would one create a RGB geotiff from a sentinel 2 data package using GDAL?

I noticed that seeing the RGB images in SNAP they seemed dark. What tools do we have to auto adjust images to best possible visual appeal?