In a recent article from CNBC, they say: ”Trump will dial back his trade pressure if markets tank.”
Dial back/down is defined by Longman Dictionary as an AmE phrasal verb meaning:
to reduce something or make it less extreme.
Etymonline doesn’t mention the meaning of dial back/down, while The Grammarphobia, in an interesting piece on the evolution of the meaning of “dial”, cites:
(“Dial down” showed up in its literal sense in 1935, and figuratively in 1988, according to citations in the Oxford English Dictionary.)
It is not clear what “literal sense” referred to, anyway I’d like to know how the figurative sense of “reduce pressure on something” evolved out of dial adding back or down.