When typing and formating content in FileMaker pro fields, the following keyboard commands can be executed when the associated commands are enabled in the FileMaker menu commands.
(modified in FileMaker (Advanced) > Manage > Custom Menus.

Mac = Command (Apple)
Windows = Ctrl
“+” means “Hold down at same time”

• Select All = Command/Ctrl + A
• Cut = Command/Ctrl + X
• Copy = Command/Ctrl + C
• Paste = Command/Ctrl + V
• Paste Without Style =
(mac)Command + Opt + Shift + V / (Windows) Ctrl + V + Shift + V
• Plain Text = Command/Ctrl + P
• Bold Text = Command/Ctrl + B
• Italic Text = Command/Ctrl + I
• Underline Text = Command/Ctrl + U
• Left-Justify Selected Text = Command/Ctrl + [
• Right-Justify Selected Text = Command/Ctrl + ]
• Center Selected Text = Command/Ctrl + \
• Increase Selected Text Font Size = Shift + Command/Ctrl + >
• Decrease Selected Text Font Size = Shift + Command/Ctrl + <
• Insert Current Date = Command/Ctrl + (your keyboard config)