After making changes, save your project. Open the console, navigate to your project folder and execute the following command to build your app
flutter build apk --release
If you are deploying the app to the Play Store, it's recommended to use app bundles or split the APK to reduce the APK size.
To generate an app bundle, run:
flutter build appbundle
Learn more on https://developer.android.com/guide/app-bundle
You should get the APK file in the build/output/apk
folder, to install your application on your connected device run the following command
flutter install