The console
Any version of the Unreal Editor, or any game built with Unreal Engine, could have a console within it. This console has tons of variables that you can turn on or off, sometimes to display stuff, and other times to just hide something away.
If you don't know how to display the console, it is usually done using the input key ` for any game or any other game engine, and that's the default button for it within Unreal Engine, but you can change it in Input Settings of Project Settings.
Unreal Engine provides a number of console variables, which could be used at runtime in order to debug the game. However, some of those console variables are called show flags, which are implemented there in order to allow you to toggle a lot of rendering features at runtime. But that is only in the executable builds; in edit time (inside the editor) it is even easier, as the editor is a convenient place to have lots of menus and buttons, The Epic team puts them in one of those menus, which...