You can add new fonts to the app by copying the font with different weight in the following folder

Project_HOME > fonts > new_font_folder

They should contain font weight files like this:

Project_HOME > fonts > new_font_folder

> new_font-regular.ttf
> new_font-light.ttf
> new_font-bold.ttf

Don’t forget to add new font entry to following file in pubspec.yaml fonts section, open file here: Project_HOME > pubspec.yaml

And add the entry in fonts section like this

Fonts:
- family: FontNameYouDesire
  Fonts:
    - asset: fonts/new_font_folder/new_font-regular.ttf
    - asset: fonts/new_font_folder/new_font-light.ttf        
    - asset: fonts/new_font_folder/new_font-bold.ttf

Register font at app level

If you want to apply the font at application level, open following file: Project_HOME > lib > hooks_v2.dart Look for the getFontHook() method and add your font name as follow:

//you can also add a condition to change font for multiple locales as well:
FontsHook fontsHook = (Locale locale) {

    return "FontNameYouDesire";

};

//You can also use this font in a TextStyle like this
TextStyle(
    …
    fontFamily: "FontNameYouWroteInPubSpec",
); 

Read more about fonts here: https://docs.flutter.dev/cookbook/design/fonts

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