Manchester United should have been ready for this match against Crystal Palace but because the death of Queen Elizabeth II made the match postponed, I think this is an opportunity for Crystal Palace to prepare the strategy used against Manchester United considering they are currently excited because of the process of recovering the standings league premiere.
I doubt that any team which is not ready now against opponents, will not be ready with any given extra time. Crystal Palace knew that they would play against United for a long time now, and they should have watched all their games and scouted them very well, which means that they would have a strategy ready for them to begin with.
This doesn't mean they can win, if it was that simple then you would hire hundreds of scouts and get superb reports of each and every team, even each players, and then you would have winning tactics against everyone. Since it is not that simple, we are seeing United not being phased and they will probably win whenever the game happens.