Setting MinSDK Android

For flutter v2.8

Inside local.properties add

sdk.dir='<path>'
flutter.sdk='<path>'
flutter.buildMode=debug
flutter.versionName=1.0.0
flutter.versionCode=1

flutter.minSdkVersion=21
flutter.targetSdkVersion=30
flutter.compileSdkVersion=30

app-level build.gradle

defaultConfig {
    minSdkVersion localProperties.getProperty('flutter.minSdkVersion').toInteger()
    targetSdkVersion localProperties.getProperty('flutter.targetSdkVersion').toInteger()
    versionCode flutterVersionCode.toInteger()
    versionName flutterVersionName
}

Now you can use localProperties.getProperty() to read the value from the properties file.

How to change Android minSdkVersion in flutter projectStack Overflow