In Dawn Moreno's first appearance, in GI Joe #226 (March 2016), she specifically says she's 15. Since she's trying to appear more grown up, she wouldn't be cheating that number down at all.
In issue #239, just over a year later, she's identified as being 17 - something that's possible if she was just shy of her birthday in the first appearance, and has just passed it here.
And eleven months after that, time continues to move normally, because GI Joe #250 says less than a year has passed.
She's next seen in issue #255 (August 2018), having had time to enlist, go through basic training and start Ranger school, where she's able to embarrass her SERE instructors because she's just that good, and by March of 2019 she was fully through training and officially assigned to the Joe team. At that point we stop getting any overt references to her age or the specific passage of time, but we can say that for the first three years of the character's existence, time pretty much matched with the real world. If that continued, she'd be 25 when she was made into this action figure, but she can't have been born in 2001 forever, the same way Snake-Eyes and Storm Shadow can't forever have been born in the 1950s.
