Model in SITL

I have a question about SITL mode. Is it necessary to load a model when SILT is executed? If I send the HEARTBEAT message setting the type of aircraft is it not enough?

You need to load the model in Gazebo. Is that what you mean?

My intention is to load a default model that is not iris and that is a fixed-wing airplane, I have tried plane but qground detects it as a custom model and not as a normal airplane