⇒ open /System/Library/PreferencePanes/Dock.prefPane
# list all possible 'domains' we can read/write to
⇒ defaults domains
# search for all defaults containing the word 'dock'
⇒ defaults find dock
# smallest end of the prefpane slider on macOS catalina is 16, largest is 128.
# old mid 2015 laptop had 38 set, 40 looks better on 2019 16"
⇒ defaults write com.apple.dock tilesize -int 40
⇒ defaults write com.apple.dock autohide -bool true
⇒ defaults write com.apple.dock magnification -bool false
# when we are done making changes
killall Dock
This is how much the icons magnify when you hover over them
The tile size may be up to 256 pixels, so don't go any higher than that. Note that icons above 128 pixels are scaled, and you can notice some pixelation.
defaults write com.apple.dock tilesize -int 256; killall Dock
defaults write com.apple.dock largesize -int 512
defaults write com.apple.dock largesize -float 128
defaults delete com.apple.dock; killall Dock