Debug tools are great fun, although often developers often disable them before they ship these days. One game that did, though, is Control - and various details about a possible planned DLC have been revealed as a result.
Debug tools, for those who aren't aware, are tools that developers create to help them fix bugs and test their games. Examples of a debug tool would be noclip mode, which lets the developer clip through walls, or a tool that will show all the assets loaded in a particular level.
YouTuber ManFightDragon discovered that there's a set of such tools in Control, and actually demonstrates them in the above video, including the free-look camera, and various effects such as wireframe mode.
The tools let you jump to any level in the game, which is where the DLC rumor has originated. There's a few missions in there that are named "SM09 - Duck" and "SM10 - Roulette Wheel" as well as a level named "St01_MM_04_Marshall_START_Plus_PS4_SM15_Dlc " - the ending of which strongly implies, well, DLC.
The level name also contains the word "Marshall", which is likely a reference to Helen Marshall, a key character in the game. Could she be the focus of this new DLC, or at least this level?
While none of this is confirmed, and is purely rumor, its an interesting look into the game's development, and it will be interesting to see how the game's DLC story plays out.