Is there a way to apply effects to several layers at once?

Heya!

I'm a long time user of CSP but I noticed something quite unpractical: you apparently can't apply effects (like blur or noise) or modify colors (saturation, brigthness etc) on several layers at once. When I try to do so by selecting the layers I wish to modify, those options are just greyed out. So, anytime I want to, let's say, change the saturation of my colors, I have to put everything into a folder, I copy/paste it to have a backup, and I merge one of the folders to apply the modification to it. It's pretty tedious and unpractical because it means I can't use the layers anymore (unless I use my backup, but then I lose the color modification) and I'm sure there's an easier way to do it.

Anyone knows how to apply this type of modification to several layers?