Starlight was part of the originality of the show.
The boys are all kind of spoof throwaway characters but Starlight is part of the shows individuality from a digg article,
Some of the show's very best moments come from its wicked corporate satire, often seen through fresh-faced hero Starlight (Erin Moriarty), the newest member of the Seven. Her glimpse behind the scenes is hardly what she expects, as her outfit is made more revealing by the marketing team, various characters encourage her "authenticity" as if it's a cultivated false persona, and festivals featuring organizations named things like "Capes for Christ" book her for speaking engagements.
She actually has a pretty interesting background,
Starlight is an active superhero that possesses the ability to fly and emit a powerful blinding light, hence her superhero code name. Her real name Annie January, Starlight served on the conservative teenage superhero team the Young Americans in her early years where she also dated the leader of the team Drummer Boy. Anne was very religious and conservative, appealing to the good in people and with a sincere wish to do good.
If she was based on a DC character I would guess Doctor Light (Kimiyo Hoshi) who shares similar blinding capabilities and a somewhat similar suit although their backgrounds are completely different.