If you are ever mad at dragon attacks accidentally killing civilian NPCs and breaking your quests, look no further - you are going to hate this mod.
In the vanilla game when a dragon attacks a city, only the guards are trying to fight the dragon while the civilians are like "Look, a fight!" "My money is on the big one". Even if the dragon kills all the guards, the civilians just return to their daily routines like nothing happened.
The purpose of this mod is to make dragons attacks on the cities more destructive and giving impressions of Kaiju attacks in monster movies such as Cloverfield, Godzilla or Pacific Rims, or at least making them feel like the Skyrim Live Action Trailer where people are all running in fear instead of "Hey there is a dragon up there but are you going to spend any money otherwise move on". Killing dragons in this context should be more of an accomplishment.
To achieve this, I strongly recommend these mods:
Deadly Dragons - So dragons are actually fearsome creatures capable of destroying an entire city instead of donating free dragon souls and bones in the first minute they show up.
Open Cities - So dragons will attack the walled cities. If you don't kill Mirmulnir after he shows up, then there is a chance that he flies to Whiterun and obliterate the entire city so you don't have to do the stupid side quests there. Plus, I personally think that if that dragon is really capable of destroying whole Whiterun, then killing the dragon will be more rewarding when Balgruuf says "You saved our city, you are now the thane, and you are the Dragonborn"
Run for Your Lives - So the civilians are gonna run away from the dragons (at least trying to. If you set the Deadly Dragons difficulty too high, and a high level dragon shows up, then the chances are the civilians will just be evaporated before they could touch a door). Or you can just leave this one and watch the brave and fearless Nords racing to Sovngarde.
Killable Essentials and Killable Children - You know why.
Frozen Electrocution and Combustion - Just adding more sense of horror to the dragon attacks. You can try deadly mutilation, but I personally prefer this mod.

And by the way, the category says immersion, but it's not actually very lore friendly (just my personal interpretation of the lore). There is a good reason that Bethesda didn't make the dragons attack civilians in their vanilla game (at least in my CK). In the lore, the dragons return to Tamiriel to not destroy everything, but to re-establish their reign and the dragon cult. So it makes sense that the dragons will leave the civilians alive.