When you create a standard document library in SharePoint you can set the document type it will use to Word, Excel etc - However it's not using different content types there, instead it's just setting the template used in that Library by the Document content type. With SharePoint 2013 Microsoft introduced the create new document option at the top of the library views were you can select Word, Excel etc. However this again is not using content types to achieve this. You could be cheeky here and say Microsoft are not following their own guidelines:-)
I'm guessing you want to give the users the option of creating new Word, Excel etc content types from the New menu? To do this you do, as you suggest, need to create new content types for each document type you want to make available.
We do this ourselves using something like this with site collection content types that are then applied to all libraries:
- eDocument - Word Template (Default).
- Excel - Excel Template.
- PowerPoint - PowerPoint Template.
This tends to work quite well because when users upload documents they go against eDocument which is a relatively generic name. If they just click New it creates a Word document but they do have the option of creating Excel or PowerPoint documents directly as well from the New menu. The trick is obviously keeping the metadata the same for all the content types.