@WestJc
The NewDocDefaultSettings is an XML node in <Npp-install-dir>\config.model.xml respectively %APPDATA%\Notepad++\config.xml but it’s for configuring EOL format, character encoding and default (programming) language for new files, thus it is not suitable for what you want to achieve.
But you could try the NewFileBrowser plugin. It provides the ability to define templates for two programming languages which can be assigned to a keyboard shortcut.
Note: The plugin is only available as 32 bit version. You can install it via PluginManager (up to Notepad++ v7.5.9) or via PluginsAdmin (Notepad++ v7.6 and above).