How to animate or make effect of SUN or EXPLOSION in keyshot 4 ?
well, if by sun effect you mean lens flare, you have to do that on another software like after effect
and for explosion, you can always try to do with some transparent textures on some mushroom like models, and animated each of them
but that would be a lot more work than in another software
keyshot is mostly made for static renders, animations are here for exploded views
for an explosion,you can use blender. it's a free render program