The phrase "doth an about face" is a bit archaic and formal. In modern English, there are many synonyms that can be used instead to convey the same meaning. Some possible options include "performs a sudden turnaround," "makes a 180-degree shift," "reverses course," "backtracks," "changes direction," "turns tail," or "does an about-turn." All of these phrases can be used to describe a sudden change in direction or action, often in response to new information or circumstances. As with any synonym, the specific choice will depend on the context and tone of the writing or speech.