My daughter's iPhone X got into a state where the touchscreen didn't respond to any touches. We force-restarted it several times by doing the "Up Volume, Down Volume, Hold Power" sequence, but it did not work -- the touchscreen stayed unresponsive.
I plugged it into my Mac with a lightning cable and went to Finder (because iTunes isn't available anymore). Clicking on the iPhone asks me to Trust it, but clicking Trust just results in a spinner. I think it wanted me to log into the iphone and tap Trust there, but of course I can't -- the touchscreen wasn't responding.

So, I figured out this alternative sequence.