Compared to a featureless earth, how would you expect the himalayan mountains to affect the gravitational force in that location?

The gravitational force would be higher than expected, as such forces would cause a major disturbance to a "Featureless Earth". good luck! :)

From the said comparison, we can conclude that gravity is all about density. So the places containing maximum mass will definitely have more density. But also at the same time, if we consider in terms of altitude or the elevation, then the places where the elevation is high enough from the mean sea level, the gravitational force of attraction is weak. Thus mountains will have weaker gravity.