Do you need to tweak the font sizes in a placeholder or object to make it fit or balance the slide? Decrease/Increase font size with Ctrl+Shift+ the less than < (decrease) or > (increase) key (Ctrl+Shift+</>).
If you don’t want to search the ribbon for just the right tool to change your fonts, use the Ctrl+T shortcut to bring up the Font Dialog box and get them all at once.
To quickly enter or edit Text inside an object, select the object and press Enter. Once in edit mode though, Enter will give you a line break.