All the awesome things you forgot your Mac could do
1. Do unit conversions in Spotlight
You might already know that Spotlight is already capable of doing basic calculations, but in High Sierra you can do something extra: unit conversions.
2. Talk to and listen to your Mac!
Before macOS Sierra, the Mac's ability to listen to you as well as talk was already really impressive with its Dictation tool.
Siri can even launch or close apps for you as well as store the results of your queries inside the Notifications area of the OS for later use. Just press Command+Space and get to asking.
3. Automatically hide and show the menu bar
you can hide the menu bar. Open System Preferences, go to General, then click "Automatically hide and show the menu bar."
When you tick this box off, the menu bar will reappear as you glide your mouse arrow towards the top of the screen, allowing you to get at all your menus.".