One specific and relatively common version of this are people who believe that women have a lower standard deviation on measures of IQ than men. This belief is not incompatible with believing that any particular woman might be astonishingly intelligent, but these people all seem to have a great deal of trouble applying the latter to any particular woman. There may be exceptions, but I haven’t met them.

I'm skeptical of the notion that people tend to lower their intelligence estimates of women they meet as a result of this as opposed to using it as an excuse to reinforce their preexisting inclination to have a lower intelligence estimate of women than of men.