Light hardness by itself does not make colors more saturated. If hard light and soft light produce the same exposure, they will not inherently change saturation.

What matters more is exposure and the light’s color. Colors tend to look strongest when they are recorded around the midtones; if you overexpose them they wash out toward white, and if you underexpose them they lose detail toward black. The color temperature or tint of the light source can also shift how colors appear.

In practical terms, hard light may seem to increase “punch” because it creates stronger contrast and more defined shadows, but that is not the same as true color saturation. So the useful rule is: saturation is affected mainly by exposure and the spectral/color characteristics of the light, not by whether the light is hard or soft.