Currently the automatic fluid typography is only available for all breakpoints, so it just scales fluidly between typescales from the largest to the smallest breakpoint.
But sometimes you want that bit of extra control and set custom typescales for different breakpoints, which currently has to be done manually and is quite a hassle.
I’m thinking it could be done this way: Make it available on all custom breakpoints, but also make it possible to enable/disable. If nothing else is enabled below ‘all breakpoints’, it scales from largest to smallest as it currently does. But if it’s enabled on custom breakpoints, then the automatic fluid typography for that breakpoint takes over when that viewport size becomes active.