You can replace those (as you wish) as you mentioned in your question.
CommandGroup(replacing: .newItem) { EmptyView() }
or
CommandGroup(replacing: .newItem) { }
According to the document. You can’t modify or remove the Apple menu items as expected. Which is actually, perfectly reasonable.
The Apple menu, which is always the first item on the leading side of the menu bar, includes system-defined menu items that are always available. You can’t modify or remove the Apple menu
Best