Based on where the first shot is landed like on the gut or head it could lead to that attack being fatal, and she can adjust the attacks size, Sukuna could have a huge
donut in his stomach the first shot ending the fight instantly.
My point is, Makima isn't seen from that point on, if Denji and her underlings didn't succeed she would resort to the ritual just as she did previously when her underlings failed in the Katana Man arc
She would just leave from that point on is what I'm trying to say. Mainly just summon her underlings then dip, the moment Sukuna activates his CT to watch behind the scenes through the senses of her underlings
I don't think she would be scared but it would shift her plans/tactics, it would be giving Makima the "I am dangerous" aura which is another reason why Makima would go behind the scenes to see the reason behind this aura by watching through the senses of her underlings