Movies exerted a great deal of influence on people's lives during the so-called Roaring Twenties. They presented a world of fantasy and glamor into which ordinary cinema-goers could momentarily escape from their drab everyday lives. Growing numbers of Americans, especially the young, lived vicariously through the lives of movie stars, who became household names, worshipped and adored by millions.

The 1920s saw a veritable explosion of movie magazines, which generated and sustained a thriving culture of celebrity. Millions of Americans were eager to read all about their favorite film stars, and movie magazines were only to happy to cater to the public's growing fascination with the stars of the Silver Screen.

During the 1920s, more and more actresses became fashion icons. Long before Instagram, with its vast army of style gurus and influencers, even existed, film actresses were seen as trend-setters, influencing how women across America styled their hair and what kind of clothes they wore.

Indeed, movie stars became so influential that numerous groups of concerned citizens were established to protect the youth of America from what they saw as a rising tide of immorality emanating from Hollywood. Many movie stars were notorious for leading sybaritic lifestyles, and the self-appointed guardians of public morals were anxious to ensure that such riotous behavior should never become normalized among the population as a whole.

Movies were quite influential in the 1920s. They explored issues that were considered taboo, such as sex, drugs, and violence. While they did not show these things like some restricted movies today, they used innuendo to get their point across. Religious groups nationwide claimed that the movies were eroding American values and organized boycotts of movies and actors accused of salacious things in the tabloids, such as Roscoe "Fatty" Arbuckle, a famous comedian who had his career ruined when he was accused of murder. The risqué nature of the movies of that era led to the creation of a ratings system for movies, which is still used today.

The movies also retold classic stories or tried to convey history in an entertaining way. Millions who have never read the book have watched Rudolph Valentino play Dracula. World War I, especially the fighter pilots, was depicted in many of the silent films of the era.

"Steamboat Willie" was the first "talkie" to feature Mickey Mouse. This cartoon would go on to launch a multi-billion dollar franchise.

Movies were part of the growth of mass consumer culture that emerged in the 1920s.  Movies and, in particular, movie stars helped to highlight the idea of fame and celebrity.  Douglas Fairbanks, Charlie Chaplin, and Greta Garbo were examples of how people became fascinated with the life of the celebrity.  The movies were able to crystallize the belief of the time of self- love, as individuals were able to look at the screen, project their own wishes upon it, or project even their own sense of self upon it.  Movies were able to be consumed by the people, at large, and helped to feed the belief that the 1920s was a decade of self glorification and projection of self.

Movies and radio in the 1920s also made our country more homogeneous.  Immigrants assimilate into American society over time.  The media of the 1920s helped to speed the assimilation for the new Americans, as well as setting us on the path to losing our regional differences.

Everyone in the country was listening to the same music, watching the same shows, identifying with the same icons.  That which made us a diverse country was beginning to blur.

Movies in the 1920s came in both the silent and talking variety.  The first talking movie wasn't until 1927's The Jazz Singer, so while movies in the time period were many, and were a chief source of information and mostly entertainment in the major cities, you would be hard pressed to find movie theaters in the small country towns that made up much of America. 

We had our first real movie stars in the 1920s, including Clara Bow, the famous "It Girl".  She was the first genuine sex symbol in American film - until the "talkie" movie because she had such a thick Brooklyn accent it didn't come across well on screen.  Movies in the 20's were the beginning of the Hollywood industry.

I'm a bit unclear about your question. Do you mean, "What kind of influence did the movies MAKE in the 1920's?"

If this is your question, the movies of the 1920's served two main purposes. First some movies were pre-empted with news reels. These news reels where meant to educate people on current events. The actual movies were often for sheer entertainment. Critics of movies back then blamed producers for promoting and expanding the image and idea of the modern woman as flapper. Also, this was the time of pre-prohibition, and Dry groups (or supports of Temperance) argued that movies promoted drinking and other salacious activities.

Now if your question is about what influenced movies in the 1920's, a lot of movie ideas came from books, plays, and operas.