RGB data into GeoTIFF


I’m trying to work using GDAL in Python with GeoTIFFs images generated using Snap (Sentinel 2). This GeoTIFF only contains the B2, B3 and B4 bands (RGB). Nevertheless, when trying to open these files with GDAL, first I get a warning, and when I try to access the values of each band, instead of the expected range from 0 to 255, I get a completely different set of values, most likely the colour histogram.

Is there any way to obtain the exported GeoTIFF in this format?