Enhanced Dictation
A macOS feature that lets you dictate offline, without an Internet connection. With Enhanced Dictation, you can use dictation commands (also known as spoken commands) to perform tasks and control your Mac while dictating text. OS X v10.11 or later provides an option to use a dictation keyword phrase so you can use dictation commands even when you’re not dictating text.
The first time you turn on Enhanced Dictation, and when you add languages to use with it, macOS downloads additional software that allows Dictation to work offline. The amount of free disk space required to download this software varies depending on the language. After the additional software is downloaded, you can dictate even when an Internet connection is not available.