short commando for capital letters

By default, there is no keyboard shortcut to apply Pages Format menu : Font : Capitalization : All Caps. You can however, assign one in System Preferences : Keyboard : Shortcuts : App Shortcuts.

On the preceding panel, select [+] and then Pages from the [ Application ] menu. Next, enter All Caps, for the Menu Title, and the keyboard shortcut, which you must be very careful that it is not used elsewhere in Pages. Then click Add. Now, when you select text in your Pages document, your keyboard shortcut selection will immediately make it All Caps.

I recommend that you study the currently assigned Pages menu shortcuts, before you arbitrarily pick one in paragraph 2.

Here is how my All Caps menu item appears after setting it to control-U per paragraph 2.