Daring Fireball describes how to restore the old trick of slow motion MacOS Dock effects:

In the midst of recording last week’s episode of The Talk Show with Nilay Patel, I offhandedly mentioned the age-old trick of holding down the Shift key while minimizing a window (clicking the yellow button) to see the genie effect in slow motion. Nilay was like “Wait, what? That’s not working for me...” and we moved on.

What I’d forgotten is that Apple had removed this as default behavior a few years ago (I think in MacOS 10.14 Mojave), but you can restore the feature with this hidden preference, typed in Terminal:

defaults write com.apple.dock slow-motion-allowed -bool YES

Then restart the Dock:

killall Dock

Or, in a single command:

defaults write com.apple.dock slow-motion-allowed -bool YES; killall Dock

I had forgotten that this had become a hidden preference, and that I’d long ago enabled it.