Run your envelope into offset and attenuation and fiddle about. Ideally you want attenuation of the envelope, an offset added to / subtracted from it, then attenuation of that signal (the air attenuator). That way you can really dial things in. Maths or SPO work well for this.
I’ve also found using multiple versions of the same envelope into mangrove (or its modulator / filter) to be useful / fun. Remember to modulate the envelope shape as well, since variable expressivity is key to horn playing. Horns have such a wide variety of timbres, and mangrove is so good at producing them, that quickly iterating on different signal routings and dialing things in will almost invariably bring the brass out