I just saw an incredible Facebook reel of a voice actor, Shelby Young, saying the same thing in a striking range of theatrical voices, and I still wonder. How much of her true vocal fingerprint is unavoidably there?
https://www.youtube.com/watch?v=DyNnyeu_kPU
(As a fan of old movies, "Vintage" was particularly impressive to me -- she is impersonating not just voices but also the choice of tonality those actors made in light of recording technology)