Hidden lock screen menu

Hi, I was just holding my phone and tapping randomly and noticed the magnifier was on my lock screen. Touched around to get it to go away (phone was still locked) and a black menu came up with some hidden options including grayscale and screen filters. Hit grayscale and accidentally closed the menu and couldn’t change it back. It was off in accessibility’s and resetting didn’t fix it. Had to completely reset setting on the phone to fix it. Anyone else find this hidden menu and know how to get it?