Spider Man: Into the Spider-Verse is a particularly richly animated film with an amazing variety of animation styles used to reflect the different universes its multiple spider characters come from. Every frame looks like a outstanding example for comic book art, showing a dedication to animation excellence that most viewers will never notice (at least until they get a digital copy they can freeze frame).
Some commentators have mentioned that the creators also manipulated the animation speed (normally animations are shot with two successive frames identical, giving, effectively, 12 rather than 24 unique frames per second). Some, but not all, claim that the creators shot some of the more at 24 unique frames per second to create specific visual effects.
Is this claim true? Does the movie contain multiple frame rates? Which sections of the movie are modified from the normal 12 fps animations and what effect was this intended to create?