There's tons of movies that I think are a must-see (Tampopo, Roman Holiday, Moonlight, Amelie etc.) and trying to recommend any made me realise how much I love watching films... but I'd start with this one. It's about Living, with a capital T, and it's got plot, beautiful scenery etc. I also think it's a straightforward way to see what films do versus documentaries or other visual media.
I first saw it as a bored volunteer at a film festival, killing time between two other movies I really wanted to see instead hahaha go in with zero expectations.