In 2020, Zac Efron, who played Troy Bolton in the original trilogy, said that he would be open to returning for a fourth movie. He said, "I would definitely be interested in doing another one. I think it would be a lot of fun."
However, Vanessa Hudgens, who played Gabriella Montez in the original trilogy, has said that she is not interested in returning for a fourth movie. She said, "I don't think it's something that I would be interested in doing."
So, while there are no official plans for a fourth High School Musical movie, it is possible that one could be made in the future. However, it seems unlikely that the original cast would all return for a fourth movie.