Settings is Windows App Sdk WinUI3 .Net Unpackaged desktop application. More details about Windows App Sdk can be found here. More details about WinUI can be found here.
The Settings project .Net WinUI3 based project which follows the MVVM architectural pattern where the graphical user interface is separated from the view models.
The UI Components are part of PowerToys.Settings project. It contains the xaml files for each of the UI components. It also contains the Hotkey logic for the settings control.
The Settings.UI.Library project contains the data that is to be rendered by the UI components.
The function of the settings runner project is to communicate all changes that the user makes in the user interface, to the runner so that it can be dispatched and reflected in all the modules.