My 2020 12.9 iPad locked up when I paired it with a 2018 full-size magic keyboard. The accessibility menu blocks me from logging in or shutting down. How do I get out of this trap?

When I paired my 2020 iPad 12.9 with my 2018 full-size magic keyboard, using a cal digit usb-c Pro dock, I could enter text in the Safari search window. But when I opened the full accessibility menu of keyboard commands, that window covers up my iPad home screen. I cannot close or escape that menu screen. As a result, I cannot shut down, cannot re-enter my passcode, cannot restart or reset. The 2018 keyboard does not work with most of the keyboard commands. How do I escape this trap?