Looking sharp is an idiom that means to look presentable or well-dressed. There are many synonyms that can be used to express the same idea. "Dress to impress" is a common phrase that communicates the same sentiment as "look sharp." "Clean up nicely" is another option that is often used. "Be all dressed up," "look snazzy," and "be perfectly groomed" are other ways to express that someone looks their best. "Be on point," "be on top of your game," and "be polished" can also convey the concept of looking sharp. Ultimately, the choice of synonym will depend on the situation and the speaker's personal preferences.