2 Sam 21:20
20 And there was yet a battle in Gath, where was a man of great stature, that had on every hand six fingers, and on every foot six toes, four and twenty in number; and he also was born to the giant.
KJV
Deut 3:11
11 (For only Og king of Bashan remained of the remnant of the Rephaim; behold, his bedstead was a bedstead of iron; is it not in Rabbah of the children of Ammon? nine cubits was the length thereof, and four cubits the breadth of it, after the cubit of a man.)
ASV
The Rephaim was a proper name for the giants. A cubit on average is a measure from man's elbow to the finger tips, about 18 to 20 inches. So...
Og's bed was about 9 feet wide by 13 feet long. And why else would the Scripture be written there about Og's bed if its huge size was not representative of Og's great size as a hybrid giant?
Num 13:30-33
30 And Caleb stilleth the people concerning Moses, and saith, 'Let us certainly go up — and we have possessed it; for we are thoroughly able for it.'
31 And the men who have gone up with him said, 'We are not able to go up against the people, for it [is] stronger than we;'
32 and they bring out an evil account of the land which they have spied unto the sons of Israel, saying, 'The land into which we passed over to spy it, is a land eating up its inhabitants; and all the people whom we saw in its midst [are] men of stature;
33 and there we saw the Nephilim, sons of Anak, of the Nephilim; and we are in our own eyes as grasshoppers; and so we were in their eyes.'
YLT
God had told the Israelites back then to go to those lands where those giants lived and destroy them. That is the reason He told the children of Israel to literally wipe out the inhabitants of certain specific nations in the land of Canaan. So when those two Israelites spoke of the Nephilim being in that land, and they felt like grasshoppers in comparison, saying that did not set well with the other's faith in God's commandment.