iPad backlight dims the goes out despite auto dim shut off

iPad 9th gen running OS 17.4.1. Accessibility -> auto dim is turned off. Low power mode is off. True Tone is off. Night shift is off. It’s set to light mode. It is cool to the touch. Auto lock is set to two minutes.

I want the iPad to go to the Lock Screen but *stay on*. It’s always plugged in and is only used for FaceTime for my elderly mom. It sits on the side table and is set to auto answer when I call. But after I call I want it to stay on and auto lock/time out to clock and weather. What am I doing wrong? Why isn’t there a “lock screen” setting for battery vs. plugged in like my MacBook has?!?