Option-Command-K
Open the Emoji & Symbols window
Control-Command-Space
Minimize a window
Command-M
Minimize all windows
Option-Command-M
Enter full-screen view
Control-Command-F
Action
Shortcut
Make the text bigger
Command-Plus Sign (+)
Make the text smaller
Command-Minus Sign (–)
Insert a line break or create a new paragraph in a message
Option-Return or Shift-Return
Apple Support article: Mac keyboard shortcuts