This is a paid asset, but now you can download Smoke & Ember FX Free.
Detail this asset from Unity Store: Original Link
Smoke & Ember FX v1.0
“If possible, please buy the package to support the developer”
Smoke & Ember FX is a collection of warzone inspired effects. The asset is crafted into scenes that may function as menu backgrounds for action and/or war games. Features desktop and mobile versions.
The effects can also be placed into game environments.
WebGL Demo | WebGL Mobile Demo
– 5 background scenes
– 5 mobile background scenes
– Extra bonfire scene
– Hi-res & low res smoke spritesheet
– 6 prefabs
– Smoke FX
– Ember FX
– Falling Ash FX
– Flare FX