Vice President Kamala Harris has churned through her office staff, raising questions about her management style and leadership abilities as she advances unchallenged toward the Democratic presidential nomination. Researchers who analyzed payroll data found an “extraordinarily high” exodus rate from Ms. Harris’ vice presidential office. Those who have worked for her over the past decade report that she was a tyrannical boss who terrified her employees, cursed, discouraged direct eye contact and made employees stand at attention when she entered a room. One Democratic official whose son worked as an intern for Ms. Harris during her years as California’s attorney...