In Flutter, you can check the device's operating system version by using the `Platform` class from the `dart:io` library. Here are the specific steps and example code:

1. Import the `dart:io` library:
```dart
import 'dart:io';
```

2. Use the `operatingSystemVersion` property of the `Platform` class to retrieve the operating system version:
```dart
String osVersion = Platform.operatingSystemVersion;
```

This property returns a string containing the operating system version. You can leverage this approach to implement different logic or provide specific features tailored to varying operating system versions.

Example code:
```dart
import 'dart:io';

void checkOSVersion() {
  String osVersion = Platform.operatingSystemVersion;
  print("Current operating system version: $osVersion");
}

void main() {
  checkOSVersion();
}
```

This function outputs the device's operating system version to the console.

How to Check Device Operating System Version in Flutter?