Over his decades in the public eye, former President Donald J. Trump has a well-established history of making degrading and racist remarks about women, people of color and pretty much anyone else who crosses his path. It is a proclivity that dates to his days as a reality television star and that has only expanded in the meme-driven era of social media. In the words of Senator Kevin Cramer, Republican of North Dakota, Mr. Trump is “an equal opportunity offender.” But in Vice President Kamala Harris, Mr. Trump has found a particularly complicated and risky target for his trademark brand...