Versions of HyperCard previous to 2.0 do not support cards of different sizes, only the size of a compact Macintosh display, 9 inches.
Version 2.X and later does allow custom sizing of HyperCard windows however. But you can't resize a window "on the fly" to fit a large monitor. A card shows up as a window with no grow box or scroll bars and remains the same size as originally defined when the stack was created unless you specifically select "Stack Info..." and resize the window.
You can, however, put the card anywhere on a large screen. You can also make it easier to get to the tear-off tools menu or the message box by putting them outside the window.