There are several synonyms that can be used in place of the phrase "act the part." One option is to say "play the role," which is commonly used in the context of acting and theater. Another possibility is to use the phrase "assume the role," which suggests taking on a particular identity or responsibility. A third option is to say "embody the character," which conveys a deeper level of immersion into the role or persona being portrayed. Other synonyms for "act the part" might include "perform the character," "take on the guise of," or simply "act." Ultimately, the choice of synonym will depend on the context and the tone of the sentence.