How to kill an app in LineageOS 18 (Android 11) by holding the back button

How can I kill an app by holding the back button in Lineage OS 18? One of the first things I've always done when installing a new Android was to enable developer options, then scroll down to the very bottom and enable the toggle for `Kill app back button" > Kill the foreground app by long-pressing the back button I just upgraded to LineageOS 18, and I was very sad to discover that this option is missing! How can I replace this functionality on LineageOS 18 so that I can force-close misbehaving apps by holding down the back button?