Going from a pre-snap man-coverage look to cover-2 post-snap can be a really effective disguise because many of the routes that often work against man coverage can be taken away by cover-2.
You can see a couple of examples of this below.
This first play was from a 2021 game between the Cowboys and Chargers. L.A. faced a 3rd-and-4, a typical man-coverage down-and-distance.
Dallas had established earlier in this game that when playing man coverage, cornerbacks Trevon Diggs, Anthony Brown, and Jourdan Lewis would match up to wide receivers Keenan Allen, Mike Williams, and Jalen Guyton respectively. And that’s how they lined up at the snap here: