Diana, the young princess of Themyscira, invited several of her young friends and fellow superheroines to visit her island and train with her. She has an idea about creating their own junior "Justice League"...Diana/Wonder Girl's friends here are: Rachel Roth/Raven, Kara Danvers/Supergirl, and Courtney Whitmore/Stargirl.
(I've not actually seen Stargirl yet, but I do have the first season DVD and will definitely be watching it soon! August 2021)
I'm assuming this is some sort of alternate universe interpretation of the characters seeing as Diana, Kara and Courtney are depicted as about the same age as Rachel. Indeed, I think the canon depictions of Diana/Wonder Woman had her being thousands of years old, with an extended lifespan (or maybe even eternal life) being one of her superhuman traits.
Yes, this is loosely based on portrayals of the respective characters in current TV series and movies, but an alternative universe where they're all the same ages.
Raven in the Titans series (played by Teagan Croft) and Stargirl in her own TV series ([played by Brec Bassinger) are I believe both high-schoolers anyway.
Supergirl is based on the depiction of young Kara by Malina Weissman from earlier seasons of the Supergirl TV series, when the young actress was about 13/14yo (but playing younger).
Wonder Girl is based on her depiction in the DC movies by Emily Carey, again in her early teens.
But yes, as I recall Wonder Woman in canon is several thousand years old in the present day (I have the figure 5,000 in my head for some reason), although this appears to be just as much due to her Amazonian heritage as her Olympian side.