I haunt the used book stores looking for 50’s SF books like that. Great stuff!
Edgar Rice Burroughs wrote a novella about role reversal. It was about a distant blck race that had white slaves. It was very insightful and of course called racist.
There is another book called “Black No More”. It was written by a black conservative writer in the first half of the 20th century. In the book, a scientist invents a machine that turns black people white. All the black people condemn it, but slowly but surely black people start to disappear. There are characters in it like Jesse Jackson and Al Sharpton who hate the machine because it is hurting their livelihood. It is the Atlas Shrugged of race relations. Not much of an ending though.