Magna porta or porta magna?

Textbooks Wheelock's Latin
1

Page 14 of Wheelock shows the declination in order of:
Nom porta magna
Gen portae magnae
etc.

Page 15 of Wheelock, under “Adjectives, Agreement and Word Order”, 2nd line, gives the example of
magna porta

and near the end of that same paragraph states that “…adjective followed the noun… exceptions were adjectives denoting size [check for ‘magna’] or number…”

Which is it?
Can it be either? If so, is one more common?

Thanks in advance.

2

It doesn’t matter terribly much. Size and number do tend to come first, while the others tend to come second, but that order might be reversed for the sake of a predicate adjective (porta magna est, bella porta est). Be able to hear noun/adjective agreement, and you’ll pick up the orders over time by habit.