In the age of chemical photography we could adjust the contrast of black and white prints, but there was virtually no practical way to adjust contrast in color images. They didn't make color print papers of varying contrast. (Dye transfer allowed for contrast adjustment, but that was pricey, rarefied stuff.)
Today, contrast is just a slider adjustment, although it isn't quite that simple: when you adjust for more contrast you may also get more saturation (see panel 8) which is often a problem. (You can always adjust back the saturation if you want more contrast without more saturation.)
Bottom Line: Contrast is a powerful processing tool that means as much in color as it does in black and white — it is just harder to manage in color.
85mm, f 1.2, 1/4000, ISO100
*I created these examples by adding levels and curves adjustment layers in Photoshop because my first tool, Lightroom, didn't let me take it to absurd levels.