My 4.5yo asked how cartoons are made. We had a lot of fun with some cardboard cutouts and recording with a phone, but I guess she wasn’t satisfied with the results since she asked “ok how are REAL cartoons made”?
I'm not sure if your 4.5yo is old enough to try Scratch[1] but nothing is too young these days. My elder got into Scratch around that time. These days, my younger one is into https://code.org and she make things go around, do stuffs, etc.
You could try showing her some documentary going over how some particular professional animation was made in detail. It sounds like she doesn't just want to make her own kid version of animation, but rather wants to learn how professional animation is done.