PluginsMap

class MyPlugin extends Plugin {
	public static pluginName() {
		return 'MyPlugin' as const;
	}
}

declare module '@ckeditor/ckeditor5-core' {
	interface PluginsMap {
		[ MyPlugin.pluginName ]: MyPlugin;
	}
}

// Returns `MyPlugin`.
const myPlugin = editor.plugins.get( 'MyPlugin' );