Stuck in Power Off Window

I have an iPhone 11. The initial problem I had was that the phone was not responsive to scrolling, swiping nor tapping. So I quit all open apps, tried again ... no change, problem persisted. The next step was a Restart. Now, I am stuck on the restart page but because I can't swipe, I can't drag the "slide to power off" button! Also, the XCancel button at the bottom of the screen is totally unresponsive.

So I am stuck permanently on this Power Off window. Strangely enough, the - swipe down and to the left - still works to get me to the Control Centre window and here, miraculously, all the icons are responsive to taps and a tap on the window itself then gets me back to the Power Off window where, again, nothing is responsive - so I am stuck. I would like to shut the phone off and then reboot to see whether the original problems would resolve. Any ideas?