https://tvline.com/2021/03/30/the-flash-bart-allen-impulse-cast-jordan-fisher/

He'll play Bart Allen, “the fastest teenager on the planet” who is Barry and Iris' son. This is a departure from the comic book where Bart is the son of Tornado Twin Don Allen.

Check out Jordan Fisher as The Flash's Bart Allen/Impulse (https://tvline.com/2021/05/21/the-flash-first-look-jordan-fisher-bart-allen-impulse-episode-150/)

Fisher will make his debut as “the fastest teenager on the planet” on The Flash's 150th episode.