Yes, there are quite a few. Some 'peggy dies civil war fanfic' stories are very popular among fans. You can check out fanfiction platforms like Archive of Our Own. There you'll find different interpretations of this scenario in the context of the Civil War universe.
In the fanfic world, the public's reaction would be huge. Spiderman was a beloved hero. There could be mass protests against the superheroes and the Civil War in general. The remaining superheroes would have to deal with this public outcry while also mourning the loss of Spiderman. They might also start to question their own actions and the future of superhero - ing without him.
Well, one way could be that in the chaos of the Civil War, Spiderman might be caught in the crossfire between the two sides. Maybe he tries to stop a particularly violent clash and gets overpowered by the combined forces accidentally. Another possibility is that he's betrayed by someone he trusts on one of the sides, leading to his demise.
There are a few significant deaths. One of them is Goliath, who is tragically killed during the battle. Also, some minor characters lose their lives, but their impact is relatively smaller compared to major ones.
The Captain America: Civil War comic doesn't feature a lot of prominent character deaths. It's more about the ideological divide and the battles that ensue rather than major fatalities. Some lesser-known characters might be killed off to add tension and drama.
In some fanfictions, Spiderman might die due to a miscalculation in his powers during the battle in Civil War. Maybe he tries to overextend himself to protect civilians or other heroes and gets caught in a cross - fire that his body can't withstand.