Minimising visual effects in Catalina

The free utility OnyX will let you turn almost all of this useless "eye candy" off. I've been using it for years. Make sure to download the version of OnyX that matches which version of macOS you're using.

https://www.titanium-software.fr/en/onyx.html

You're mainly interested in turning the many graphics effects off.

I’m still left with some scaling from the dock and the shadows, but the scaling effect is diminished.

Yeah, there isn't a way to turn scaling (or genie, or suck) off. But killing the other effects makes scaling less annoying. I've never seen a way to reduce or eliminate the Finder shadows.

i'm not sure i understand. are your application icons "bouncing" when minimizing, maximizing? or are you referring to the application scaling down in-between the "download folder" and trash bin?

if it's the scaling down that bothers you:

Apple Menu>System Preferences

choose "dock"

check the box "Minimize windows into application icon" and also go to "minimize windows using:" and choose "Scale effect"

the animation will diminish somewhat, but will still be there, just hidden behind the icon.

one last thought. you can stop the app icons from growing bigger when you hover over them by unchecking the "Magnification" box in your "dock" preferences

to remove the opening/closing animations:

Apple Menu>System Preferences

choose "dock"

uncheck the box for "animate opening applications"

i'm not sure about removing shadows.