Custom Ini file path after package

Sorry for the lack of completion on that answer. I even had to look it up myself now to understand where those are used haha

The custom address can be passed when you read/write the values manually using the global GConfig. Like in this example from the Engine:

void UCineCameraSettings::CopyOldConfigSettings()
{	
	const FString SettingsConfigSection(TEXT("/Script/CinematicCamera.CineCameraSettings"));

	FString OldDefaultLensPresetName;
	if (GConfig->GetString(*CineCameraConfigSection, TEXT("DefaultLensPresetName"), OldDefaultLensPresetName, GEngineIni))
	{
		GConfig->SetString(*SettingsConfigSection, TEXT("DefaultLensPresetName"), *OldDefaultLensPresetName, GEngineIni);
	}
	// ...

You’d replace GEngineIni with your own path.