What is the tool they use in slides to highlight some part of code and dim down the rest? Is it a feature in Idea?

I too was wondering this - it’s real nice.

When I do this I just duplicate the slides and colour the code I don't want to highlight grey, and then transition between those. I don't think there's a much better way to do it.

I do it the same way.

In keynote you use Highlight by Bullet point. You can do it on single slide

Can it be done on windows? Anybody?

Or Linux?

Yeah, my slides are just new duplicated versions with the color + Magic Move transitions I want in between them. I didn't have many actual slides but the slide count comes out to around 160 still