What were some of the impacts that the New Era of 1920s had on women and minorities?
We should also include the idea that America had many different ethnic minorities at this time, due to the large immigrant population. Poles, Italians, Russians, Jews all came here in large numbers, and each faced discrimination in the 1920s. As the Ku Klux Klan exploded to nearly 5 million members, new laws restricting immigration were passed, such as the Emergency Quota Act and the National Origins Act. Women among these minority populations faced dual discrimination, even during a time that many see as more liberating for women.
While there were a few million women who might be called flappers at the time, most women were conservative in values and religion, and frowned on women becoming more politically active, or leaving the home for the workplace. The women who did enter the work force mainly did so in professions like teaching, nursing or clerical jobs.
African-Americans did not share in the nation's prosperity in the 1920s, nor did Native Americans, and faced as much discrimination and segregation as ever.
I would say that the 1920s helped to bring about a great deal of social change to minorities and women. Certainly, while the fashion of the time period was controlled by companies and corporations that were run by men, I believe the idea of being able for a woman to be in control of her own sexuality was rather prominent. The flapper era espoused that women could be something other than demure and meek. This was in stark contrast to the depiction of women that dictated a domesticated existence that did not include notions of sexuality, sensuality, and the idea of being able to empower oneself through cosmetic and fashion means helped to impact the narrative of women. At the same time, the Harlem Renaissance emerged in the 1920s, which greatly expanded what it means to be black in America. Thinkers like Hughes and Hurston did much to articulate the condition of living in America as a person of color and how this reality was uniquely different from the experience of being White in America.
I am assuming that you are talking about the United States. If so, the 1920s was a time in which women and minorities (mostly African Americans) had expanding opportunities and more freedom.
By the 1920s, more blacks were living in northern cities (because they had come north during WWI). This allowed them more freedom and dignity than they had had in the Jim Crow South. This led to such things as the Harlem Renaissance (but did not really lead to much in the way of rights).
In the 1920s, we saw the "flappers." They are emblematic of how womens' lives were changing. Women were coming to be "allowed" to do more things and to have more freedom in their lives.