C’mon dude. It’s all there.
To open a level:
UGameplayStatics::OpenLevel(this, FName("/Game/tests/map1"), false, "XXX");
The options string is in:
OptionsString
in the game mode.
For example, if in the game mode you write this up:
void AFPCPPGameMode::BeginPlay()
{
Super::BeginPlay();
UE_LOG(LogTemp, Warning, TEXT("Options > % s"), *OptionsString);
}
It will log “Options > XXX”.