How to highlight object in render with material on top?

How to highlight object for render? I need to do video about technical piece, and when narrator mentions some detail, it should be highlighted.
Is it possible to set material on top of other materials and animate it’s transparency?

use a mix shader with an emissive material and animate the mix factor?

You can use an “add shader” node to add an emission shader on top, and plug a fresnel node into the strength input, for instance (you’ll get a sort of rim highlight). Use a math node set to multiply in between the fresnel and the emission, and animate it between 0 and 1.

Yeah, mix and add shader could work, but what if i have multiple materials on object, and i want to apply material with emissive on top of everything?

Add your nodes to the right end of the tree

It might be the easiest to simply use a glare node on the relevant object in the compositor.

It would be nice if you could share some image or video of the kind of object you are using (or even better, a .blend file.) and the kind of effect you are looking for.