Fresnel and specular colour
Yes, because refractive index can vary with wavelength. This is the origin of colored specular reflection in metals such as gold and copper; most other materials have essentially uncolored specular. At each wavelength, the specular reflectance at normal incidence is related to the refractive index at that wavelength according to the formula you mentioned.

In case you're interested, the site refractiveindex.info has data tables and graphs of refractive index versus wavelength for various materials. For example, here's gold: