With closer examination of scripture, the Bible actually never made claims of giants taller than 7 - 10 feet (2 to 3 meters).
I was going to say otherwise until I saw that you mentioned Og, who was monstrous.
So they weren't 30 foot fairy tale giants.
Not in the canonized bible we have, however, extra-biblical scriptures contemporaneous with the canonized Old Testament scriptures do tell of fairy tale giants MUCH larger than 30 feet (up to 450 ft high!).
What is important to note is that these writings were discovered as part of the Dead Sea Scrolls, which show that the Essenes and possiblty others believed this was the Word of God.
This can be located in the Book of Enoch and the
Book of Giants, which go in to great detail about "The Watchers" (otherwise known biblically as "Nephilim."), including their names.
Edited by Hyroglyphx, : Changed subtitle
"Three passions, simple but overwhelmingly strong, have governed my life: the longing for love, the search for knowledge and unbearable pity for the suffering of mankind." -- Bertrand Russell