And an age reset in 2004, and an age reset in 2011. As well as her story involving her history repeating thrice, almost like every time there's a timeline change her escape rocket ship gets caught in the time dilation ripple and lands after the Event, destined to always show up at Earth age 17 after an Event, even as other characters who debuted around the same time do very slowly get older.
Supergirl's age is weird. Like isn't she technically older than Clark? And he's in his mid-30s. But she was ... in stasis or something? But I feel like I get that weirdness because the gist of the idea was "let's introduce a Super-Girl! This one will be more legit than previous ones, she's actually Clark's little cousin! She's an El!" but then like two weeks after her debut someone was like "Hey, Otto, if Superman was literally an infant sent from Krypton the day it exploded ... how the hell does he have a YOUNGER cousin?" So she's got a little bit of weird age built-in. It's not Arisia bad or anything. Just a wacky sci-fi solution to a storytelling problem.
Actually it occurs to me that I've fallen off the Supergirl books, mainly after who was it, Steve Orlando's cool run? I liked that they added a lot of CW vibes but I'm curious if she comes across as more young adult now? Like what age is she supposed to be representing? The internship at CatCo and stuff like that feels very college-level, which at least to me feels a little more "Tim Drake & Stephanie Brown Age".
Dick of course feels like someone who, "age-wise", has recently gotten his PhD in Superheroics.
Either way I'll say that as far as looks go, in-costume, either a Dick/Supergirl or Dick/Power Girl or Dick/Superpowergirl match would at least Look Fantastic, her all blonde and nice and bright, him all raven-haired and bad-ass, but kind-hearted. Very Eowyn & Faramir.