p. 22-23:  "Gustav von Aschenbach was of a somewhat less than medium height, dark, and clean-shaven. The head seemed a bit too large for the almost dainty physique." The text goes on to describe Aschenbach's appearance in detail. Koelb says of this passage:

The second chapter closes with a kind of covert classical ekphrasis (a description in a literary work of a piece of art). It is an ekphrasis because Mann was in fact offering a description of a photograph of Gustav Mahler he had found published in a periodical; it is covert because no one reading the story without a privileged access to Mann's working notes could know that he was describing the photograph. In any case, Mann's description follows the photograph very closely, including details such as the cleft in the chin, the furrowed brow, and the slightly tilted posture of the head. Aschenhach's (Mahler's) face is then transformed into a kind of living text in which the change becomes evident in the course of the narrative (99).

Work Cited

Koelb, Clayton. "Death in Venice: A Companion to the Works of Thomas Mann." Studies in German Literature (2004) 95-113.