Unreal editable config file for package

Source code

// Config tag can be added to any UCLASS
UCLASS(BlueprintReadOnly, Config=MyConfigFile)
class PROJECT_API MyNewClass : public AActor
{
  GENERATED_BODY()
 
  public: 
  MyNewClass ();
 
  // This will create/read the config file
  UPROPERTY(Config, BlueprintReadWrite, EditAnywhere)
  FString MySavedVarToConfigFile = "DefaultValue";
 
  //From anywhere inside your class, will generate [YourProject]/Saved/Config/Windows/MyConfigFile.ini
  //SaveConfig();
}

You can then create a config file at [YourProject]/Config/DefaultMyConfigFile.ini and add in :

[/Script/PROJECT.MyNewClass]
MySavedVarToConfigFile = "Edited var"

Reboot Unreal Engine if you modify it or manually use a LoadConfig(); when needed.
You can add a SaveConfig(); in your constructor so Unreal will generate the Config file for you. Just need to retrieve it from [YourProject]/Saved/Config/Windows/MyConfigFile.ini and modify ! Think to delete the saved config file so Unreal read again the DefaultMyConfigFile.ini in editor.
Default config files will be automatically added to your package.

Reads More :

• https://docs.unrealengine.com/4.27/en-US/ProductionPipelines/ConfigurationFiles/
• https://ikrima.dev/ue4guide/application-os-generic-platform/config-files/