Note:
  Check out the google_fonts package for direct access
  to over 1,000 open-sourced font families.

Note:
  For another approach to using custom fonts, 
  especially if you want to re-use one font over multiple projects, 
  see Export fonts from a package.

Flutter works with custom fonts and you can apply a custom
font across an entire app or to individual widgets.
This recipe creates an app that uses custom fonts with
the following steps:

Import the font files.

Declare the font in the pubspec.

Set a font as the default.

Use a font in a specific widget.

1. Import the font files

To work with a font, import the font files into the project.
It’s common practice to put font files in a fonts or assets
folder at the root of a Flutter project.