Attacks in action rpgs like diablo and lost ark?

I'm just reflecting over how those games actually deals with attack collisions. By that I mean, their huge weapon attack vfx's. Huge sword swipe vfx's covering half the screen. Or a piercing spear shooting a long vfx spike through enemies. Or a flamethrower effect going out in a cone while rotating to hit as many as possible.

I'm not asking for code or anything, but I would very much like to hear other programmers thoughts on the matter.

• How do you think they deal with the actual collision for their attacks?

My own current hypothesis of how to emulate it would be some kind of particle system instantiated by an animation event trigger, and then that the collision is actually made by the particles?

The other approach I'm imagining is simply adding a collider to the character animation, animating it's size and position, fitting the vfx into it.

And how would you go about dealing with it in unity?