It was more than a decade ago, in a hallway near an arena, when Gina Carano first met Ronda Rousey. Carano was wearing big blue heels — she remembers this clearly — on her way down to the ringside seats. Rousey was an Olympic judoka with a few professional fights and a name nobody really knew yet. She walked up with what Carano now describes as “a mischievous grin,” looked her in the eye, and said, “You’re not that big.” Carano, in the heels, looked down at Rousey and said, “Hi, Ronda.” That was the introduction. They never fought. Rousey became the most famous woman in the history of mixed martial arts, won and lost the U.F.C. bantamweight title, retired, joined the W.W.E., retired again. Carano, meanwhile, went the other way: She made Haywire , for Steven Soderbergh, a Fast & Furious sequel, and then, in 2019, joined The Mandalorian as Cara Dune, a New Republic shock trooper who was meant to anchor her own spinoff, Rangers of the New Republic .…