YouTube user HelloGreedo made what is IMO the best critique of how Palpatine is portrayed. When he first appears in the OT he was inspired by the Roman and Chinese Emperors of old, but the prequels made him so goddamn evil, more akin to a mythological creature from the Underworld.
He’s talking specifically about Clive Revill’s performance in Episode 5. The prequels didn’t make Palpatine like that, Ian McDiarmid did.