Command is the Strength of Person, not only how well you project your presence, but how well you resist the presence of others. It’s almost a mixture of Charm and Willpower in a way, doing the same things those stats do, but from a different theme. As you’re likely aware if you’ve played even a few sessions of this game, it also hosts your most important Skill. Stability.
Due to its similarities with Charm, you can do most of the same things with it, with Subtle and Daze being the most obvious Extras to attach to it, should you have the sort of character whose theme is a commanding presence.
Unlike Charm though, Command is a decisive stat, “Please don’t” vs “Stop!”. As such, it’s thematic to the stat to (particularly if you’re using Subtle), to include Interference +3 (-1, only applies to commands, -1 Depleted(?)). Depleted gives is a bit of the “Mua’dib” effect of Dune, before your voice gives out, or if Subtle, until you are mentally exhausted from the efforts.
But there’s more to Command than issuing orders. There’s Stability. If you’re the central figure, the commanding presence amongst the heroes, the Captain America of the troupe, perhaps an ability to extend your Stability outwards might be nice. Radius and Controlled Effect would work well with this, you can attach an If/Then that it only applies to Stability type checks (or link it directly to the Stability skill). But… not using that If/Then would let your “Stop!” stop all enemies within a 10m radius of you!