Yes. Working in a variety of styles and mimicking pre-established styles is a very useful, but underappreciated, skill as a game artist. Some artists have more aptitude for it than others, but like any other art skill, it's something one can learn through careful practice.
While, as skylarkblue1 said, art directors aim to have each artist fill a role according to their strengths without the need for mimicry, it's also not uncommon for games, especially 2D games, to have their look driven by one artist early on, and to require more artists to continue in that style because the original artist can't complete the work quickly enough or has left. While mimicry is rarely perfect, a skilled artist can get close enough that players won't even suspect that multiple artists were involved. This kind of mimicry is probably involved in more games than you might think, especially among visual novels and portrait-heavy RPGs.