You can define a const DEF_TEXT_STYLE in a constants.dart file and then apply it whenever you want.
constants.dart
const DEF_TEXT_STYLE = const TextStyle(
letterSpacing: 1.0);
You could apply in this way:
Text(
'This is my text',
style: DEF_TEXT_STYLE,
),
Remember to import your constants.dart file.
Otherwise you could overwrite all textTheme data similar to what @glavigno said:
Here you can see all the textTheme data available in flutter.
DOCS
theme: ThemeData(
textTheme: TextTheme(
headline1: Theme.of(context)
.textTheme
.headline1
.copyWith(letterSpacing: 1.0),
headline2: Theme.of(context)
.textTheme
.headline1
.copyWith(letterSpacing: 1.0),
headline3: Theme.of(context)
.textTheme
.headline1
.copyWith(letterSpacing: 1.0),
headline4: Theme.of(context)
.textTheme
.headline1
.copyWith(letterSpacing: 1.0),
headline5: Theme.of(context)
.textTheme
.headline1
.copyWith(letterSpacing: 1.0),
headline6: Theme.of(context)
.textTheme
.headline1
.copyWith(letterSpacing: 1.0),
subtitle1: Theme.of(context)
.textTheme
.headline1
.copyWith(letterSpacing: 1.0),
subtitle2: Theme.of(context)
.textTheme
.headline1
.copyWith(letterSpacing: 1.0),
bodyText1: Theme.of(context)
.textTheme
.headline1
.copyWith(letterSpacing: 1.0),
bodyText2: Theme.of(context)
.textTheme
.headline1
.copyWith(letterSpacing: 1.0),
button: Theme.of(context)
.textTheme
.headline1
.copyWith(letterSpacing: 1.0),
caption: Theme.of(context)
.textTheme
.headline1
.copyWith(letterSpacing: 1.0),
overline: Theme.of(context)
.textTheme
.headline1
.copyWith(letterSpacing: 1.0),
),
),