Josephine's first major role was in 2017's Wish Upon, but the part that really put her on the map was the role of Tessa Young in the After movie franchise. Surprisingly, Josephine wasn't even planning on auditioning, as it conflicted with her shooting schedule for another project. As she explained to Collider in April 2019, "My friends were auditioning, and I was like, 'What's this?' I was rooting for my friends, but I was like, 'What's this tape that we're about to do?' And they were like, 'Oh, it's just this thing. You can't audition for it 'cause you need a green card and it conflicts with a job that you're shooting.' And it did, so I didn't get the audition."
The shooting dates ended up being pushed back, but since another actress had already been chosen for the role of Tessa, Josephine auditioned for the role of Molly Samuels instead. "This was one of the only auditions I've ever done, where I didn't read the script beforehand 'cause I literally didn't have time that week," she continued. "So, I did the audition and I did a callback, and then I got a call saying, 'They want you for the main girl.' Then, I read the script and was like, 'Oh, yeah, that seems like a better feel.'"