No, you do not have to see all the series before you watch Toy Story 4. This story is basically a fresh start for the toys. The adventure is totally different from the series in the past. However, you may want to have a quick view on all three existing movies in the series.
You can also watch the previous film to have a feel of how animation was in the 1990’s and how animation has evolved over the years. One thing is certain; you will not be confused if you do not see the existing series before Toy Story 4.
It is a good idea to watch all the Toy Story movies before watching Toy Story 4. The new film is groundbreaking in terms of animation. Watching it from the first one allows the viewer to be able to see the evolution of animation and seeing how far it has come since the first Toy Story came out in 1995. There are many great lessons to be learned in the film as well.
These include embracing your inner child, letting go and moving forward, never forgetting where you came from, helping children who have less than you do, and realizing the value of things and not judging a book by it’s cover. Also, sequels can be somewhat confusing if you choose not to begin with the first film in a series.