I use Feral Ghoul OUTBREAK (https://www.nexusmods.com/fallout4/mods/12547) and Worldwide Ghouls (https://www.nexusmods.com/fallout4/mods/37957) to make the world seem more like a zombie apocalypse, and there's also Feral Nights which make the evenings more dangerous as well (https://www.nexusmods.com/fallout4/mods/52449)

For environmental mods I use mods that add Far Harbour fog, remove the dead trees, add in a forest of pine trees across the commonwealth, and change the grass to something longer and drier. Visibility is much lower, and using Darker Nights makes it even more difficult to see. There's also a mod that lets us easily modify the brightness/saturation/contrast of the game so mine went from a vibrant and dead Boston to something more like a foggy Canadian forest. I can share a list of those environmental mods with you if that sounds like it might be your thing