The Ant-Man film was one made with much controversy. The main character wasn’t going to be Hank Pym (who is a founding member of the Avengers in the comics), but rather, Scott Lang. Then, there was the switching of directors from Edgar Wright to Peyton Reed. Despite it all, the movie did decently at the box office, and led to not only a sequel via Ant-Man And The Wasp (which comes out next year) but Ant-Man appearing in Captain America: Civil War, where many things happened.
One of the biggest things (no pun intended) was that during the fight at the airport, Ant-Man used a new formula to become Giant-Man. Something that he noted he never used before, and was being tested by Hank Pym in a lab. Giant-Man is a key part of the Ant-Man mythology, and apparently, we’re going to see it again in Ant-Man And The Wasp. Not just physically, but as a key part of the plot’s story.
“The events of Captain America: Civil War gave us something clear, which is: What was Hank Pym and Hope Van Dyne’s reaction to Scott having taken this technology out into the world in Civil War?” Reed told Empire Magazine (and was reported by ComicBookMovie.com). “We had a lot of fun playing around with that. And we play with size and scale a lot. I love the idea of Giant-Man.”