If you are looking to edit the config files in the saved/config folder:
if (!GConfig) return false;
GConfig->SetString(
TEXT("/Script/EngineSettings.GameMapsSettings"), //section
TEXT("GameDefaultMap"), //Setting Name
TEXT("value string goes here"), //Value
GEngineIni //file to save
);
GConfig->Flush(false, GEngineIni); // Save the config file
If you are looking to edit the config folders in the root config folder:
Look for your setting in the engine settings module
https://docs.unrealengine.com/4.27/en-US/API/Runtime/EngineSettings/
in build.cs under PrivateDependencyModuleNames.AddRange
you need
EngineSettings
and your function will look something like this: (I needed one for setting packaging maps so I used UGameMapsSettings | Unreal Engine Documentation)
bool UOVFPPluginBPLibrary::VPOVFPSetPackagingMap(FString mapPath)
{
UGameMapsSettings::SetGameDefaultMap(mapPath);
return true;
}
Either way, wrap them in a blueprint library function like you did with reading the file