Q: The Podcast App is not on my iPhone 6S

Settings - General - Reset - Reset Home Screen layout

You should find it after that

As an alternative to ManSinha's suggestion you could try to search for it first.

Use Search on your iPhone, iPad, or iPod touch - Apple Support

Maybe its hidden somewhere you don't expect to find it.  It might save you having to reorganize your screen layouts.

Go to Settings->General->Accessibility->Podcasts,  and make sure it's not turned off. 

Settings>General>Restrictions.

The Podcast app is built into iOS, it an not be deleted. It can be hidden with restrictions.

You're welcome.