I rarely notice anyone using variable fonts in real-world scenarios in any obvious way—setting aside variable font marketing animations. It's hard to tell if a variable font is used in a static way. For all I know, I'm looking at variable fonts on websites all the time without realizing it.
But I noticed a very obvious use of variable fonts when I recently upgraded to an iPhone 15 Pro. One of the features that was new to me is the "always on" display. On my previous iPhone, when it was showing the lock screen, after a few seconds it would turn off the display, fading to black. With the "always on" display, the screen dims instead, and you can still read the time and other information while it's on standby.
What I noticed was that the weight of the large text for the time changes as it dims or lights up, between a thinner weight for standby and a bolder weight for when it's lit up. The weight animates—like all those VF marketing animations—between these two states. I also recently got a new Apple Watch, and it does the same thing with its "always on" display.
Apple has been using variable fonts in its UI for a while, ever since they started using San Francisco on their devices. But this is the first time I've seen it used in a way that is only possible with a variable font.
Has anyone else noticed this, or seen any similar uses of variable fonts?