He was a month short of his 34th birthday when he ascended to the throne.
Most of the information we have about who he was as a person comes straight from Catherine herself, and she had a vested interest in making him look bad, considering she overthrew him and all. She describes him as a hideous, stupid and cruel drunk – a portrayal the show certainly leans into.
But the show also depicts him as a hopeless ruler who isn’t interested in progress, which contradicts some of the real policies he implemented in his short reign. For instance, he proclaimed religious freedom, expanded education, and made it illegal for landowners to murder their serfs. Small steps, but steps forward nevertheless.