It's hard to say for sure. There are often elements of fiction or exaggeration in many stories, so it's possible that parts of it aren't completely true.
It is indeed based on a true story. Frida Kahlo's life and her art form the core of the narrative. However, some artistic liberties might have been taken for cinematic purposes.
I think 'Frida: A Biography of Frida Kahlo' might be one. It focuses on her life and could potentially have elements related to her in a fictionalized context.