This 1992 biopic of Charles Chaplin was based on Chaplin's autobiography. It covers Chaplin's life from age 7 through his death at 88yrs old (1977).
Stars Robert Downy Jr. as Chaplin. And Anthony Hopkins is a fictional interviewer that, along with 'Chaplin', acts as a voiceover, and in cutscenes, to string together the story as it is told. The movie has an amazing supporting cast as well. Directed by Richard Attenborough, who you may remember as John Hammond (the old dude) in Jurassic Park. He's also directed other outstanding films, such as Gandhi. And if you haven't seen Gandhi - there's another outstanding biopic that I recommend seeing at least once.
I've watched maybe 10 (or so) of Chaplin's best films and I have to say Downy's portrayal of Chaplin, in the few scenes he recreated, were spot-on: mannerisms, facial expressions, body language - Downy did an outstanding job and was nominated for an Oscar for that role. As for how accurately he portrayed the off-screen aging Chaplin, I dunno - but the performance was believable and top-notch.
If you haven't seen many Chaplin films I suggest catching a Chaplin marathon on Turner Classic Movies sometime, or renting 'em or something. I'd recommend TCM because they did pick the cream of the crop of the 87 flicks he made.
When I watched the TCM marathon I was floored by how brilliant Chaplin's movies were - such that they're still amazing to this day, even the talkies. Watching Chaplin's films first really made watching this biopic that much more interesting, because you get a sense of the context of events in his life in relation to the movies he made.