I think this comparison is a bit disingenuous. Street Fighter has always had extremely stylized, cartoonish proportions on characters. Golden Axe is a beat 'em up in a fantasy setting that started as 2D pixel art. Neither of those are presenting themselves as realistic visually. The Last of Us by comparison is one of, if not the most dedicatedly realistic-looking series on the market right now, and mostly is very reasonable in-universe when it comes to the characters' physical appearances. Therefore when outliers pop up, it's way more jarring: how did Bill, a lone nutter in a town filled with infected manage to stay so plump? How did those raiders in Pittsburgh, an area outside of any safety zone, have biceps that big if they have to resort to highway robbery for resources? And yes: how does Abby stay that jacked?
Now, I'm not saying Abby or any other women can't be that jacked in that setting. What I'm getting at is that TLoU 2 doesn't provide enough context to establish, or to allow the player to make reasoned conclusions, about how she maintains her physique. No other human character in the entire game, including male ones, is anywhere near her level of fitness. The only ones that come close are the Seraphite brutes, and those could be either reasoned with untreated gigantism, or falling into the same "huh?" category as the aforementioned raiders. Sure, we see that the WLF has a well-maintained gym which Abby seems to sleep next to, but that could just be incidental. No one ever refers to Abby being a gym maniac, and we never see her do anything more physically straining than what presumably any other WLF member does (prior to her odyssey, obiviously). At best you can "well maybe" her physique: in her first flashback we see that she was pretty jacked even as a teenager. Well, maybe she's just been into lifting her whole life. Or well, maybe she frequents the gym like everyday. That's the best we get.