The phrase does not call for quotation marks, since it is not being used in any unusual sense. It has nothing to do with formality. Quotation marks are used for newly coined words, foreign words, and words used in an unusual or unexpected sense.
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AnonymousThank you so much and quotation marks are not used for emphasis?No, not at all.
AlpheccaStarsHe sold "authentic Rolex" watches on a street corner of Paris.The quotes tell us that these were really cheap imitation watches.Yes, this is one example of the phrase having its usual meaning.
Anonymousyou mean "this is one example of the phrase having its unusual meaning"?Oops! Right, thank you.