The "Jurassic World" star portrays the late Sheila Dwight in the movie, opposite Taron Egerton as Elton, and because the storyline spans over five decades, she was keen to ensure her appearance was just right onscreen as hair and make-up experts piled on the prosthetics.
"I had this really cool thing happen where my family was actually in the U.K... and I was doing all these (prosthetics) tests to kind of figure out how I was gonna look older," she explained.
"My mum came by, and we were looking at the prosthetics and we were like, 'We need more freckles...' so we did age spots and all that."
The actress was thoroughly pleased with her perfected cosmetic look, but just before she was due to film her first scene, she realised she hadn't given a single thought to the physical nature of the role.
"I was so focused on the look, it came time to actually act, and it was about five minutes before shooting, and I'm sitting there in my costume, and I suddenly got my phone out and I Googled, 'How to act old!'," she laughed.
"I was like, I thought about the wrong stuff!".
Luckily, Bryce was able to pick up a few useful hints and managed to make it work as she stepped onset: "Things came up, very helpful insights!" she smiled.
"Your movements slow down, definitely, there's some shaking that can happen. Obviously the voice changes significantly and the register drops and all of that."
And the star had to develop her role in record time: "I was cast six days before I was on camera," she revealed.
Bryce never got to meet Elton himself, but she received a wealth of information about Sheila from co-star Taron Egerton, who plays the rock legend in the movie.
"Taron was actually really, really helpful, because he had obviously spent so much time with Elton," she said. "Elton had shared with him his diaries, his autobiography, which no one else had read at that point, so there was quite a lot that he was able to share.
"And then I spoke with a lot of people independently of production who knew Sheila."