Find more at macOS defaults
defaults write com.apple.dock persistent-apps -array-add '{"tile-type"="spacer-tile";}'; killall Dock
defaults write com.apple.dock static-only -bool true; killall Dock
Highlight hidden apps in the Dock
defaults write com.apple.Dock showhidden -bool yes; killall Dock
defaults write com.apple.dock mineffect -string suck; killall Dock
defaults delete com.apple.dock; killall Dock
defaults write NSGlobalDomain "AppleShowAllExtensions" -bool "true" && killall Finder
Show hidden files
defaults write com.apple.Finder "AppleShowAllFiles" -bool "true" && killall Finder