They also don’t have to rush the timeline. The show can avoid needing to have the characters age too much by keeping the average “down time” offscreen between episodes down.
For instance, the last two episodes probably took place over a few hours. There’s no reason for it to be 2 weeks later (or 8, including the real time hiatus) in the next episode, it could pick up soon after where they left off when we meet them next in episode 6.
They can keep them young to appeal to the target audience by not having each year’s worth of episodes represent a year in real time, but still have it take place firmly within the canon.
And maybe worth mentioning, the Hageman’s last big show, Trollhunters, did have the main teenaged characters advance in age, going forward in High School, over the course of the seasons, but not really changing in appearance, so I wouldn’t be shocked if they age a little without looking any different over the course of the series on Prodigy as well.
Edit: I *just* remembered that in Trollhunters one character, Eli Pepperjack, went through puberty over the course of the series of series, by the time of the movie length finale, and grew several feet in height, and went from looking like a child to a young man, so it’s not unprecedented from Prodigy’s series creators/showrunners.