Amazon carries StarTech and Tripp Lite branded recessing adapters and front panels.

Recessing bracket: https://www.amazon.com/StarTech-com-Server-Rack-Depth-Extender/dp/B01GGKM4S8/ref=sr_1_3?dchild=1&keywords=Recessed%2BRack%2BAdapter%2B-%2BRack%2BMount%2BAdapter%2BKit&qid=1615498597&sr=8-3&th=1

Front panel with key lock: https://www.amazon.com/StarTech-com-Rack-Mount-Security-Cover-Compatible/dp/B084PBTJ7J/ref=sr_1_4?dchild=1&keywords=3U+rack+mount+front+panel&qid=1615498953&sr=8-4

​

Note: IT rack standard cage nuts will be required.