The Bible uses several descriptions
The first mention comes before the flood. Genesis names the Nephilim and calls them mighty men of old, but gives little explanation of who they were or how large they were. Christians have offered different understandings of this difficult verse. Some see a group of powerful human warriors or rulers, while others connect them with the earlier description of the sons of God. The passage doesn't settle every detail, so humility is wiser than speculation.
Later, the Old Testament speaks of the Anakim, a people associated with Canaan. Deuteronomy describes them as great and tall, and says they were known as the children of Anak. These references show that the Bible did not use giant language only for one isolated story.
There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown.
Fear shaped the spies' report
When Moses sent spies into Canaan, they reported seeing the children of Anak and compared themselves to grasshoppers. It is a vivid picture of how intimidated they felt. Yet their report should be read carefully. They also gave a deeply discouraging account of the land, and Scripture later calls it an evil report (Numbers 13:32-33; Numbers 14:36-37).
Joshua and Caleb saw the same land, but trusted that the Lord could bring Israel into it. They did not deny that the people were strong. They believed God's promise mattered more than the size of the opposition (Numbers 14:6-9). So the passage supports the reality of formidable people, while warning us not to let fear become the final interpreter of what we see.
And Joshua the son of Nun, and Caleb the son of Jephunneh, which were of them that searched the land, rent their clothes: And they spake unto all the company of the children of Israel, saying, The land, which we passed through to search it, is an exceeding good land. If the Lord delight in us, then he will bring us into this land, and give it us; a land which floweth with milk and honey. Only rebel not ye against the Lord, neither fear ye the people of the land; for they are bread for us: their defence is departed from them, and the Lord is with us: fear them not.
Og and Goliath are described more closely
King Og of Bashan is linked with the Rephaim, another people remembered for unusual size. Deuteronomy records the dimensions of his iron bedstead, presenting it as a striking sign of his exceptional reputation. Whether it was simply his personal bed or a royal object kept as evidence, the writer plainly wants readers to see Og as extraordinary (Deuteronomy 3:11).
Goliath is the best-known individual. The account identifies him as a Philistine from Gath, gives his height, and goes on to describe his bronze helmet and coat of mail (1 Samuel 17:4-5). Ancient cubit measurements do not remove every modern question about his exact height, but the story clearly presents him as a physically imposing fighter.
And there went out a champion out of the camp of the Philistines, named Goliath, of Gath, whose height was six cubits and a span. And he had an helmet of brass upon his head, and he was armed with a coat of mail; and the weight of the coat was five thousand shekels of brass.
What evidence can show
No excavated skeleton has been universally accepted as the remains of a biblical giant. That means archaeology cannot currently give a neat physical confirmation for the Nephilim, Anakim, Og, or Goliath. Absence of such a discovery does not prove the biblical accounts false, but it does call for care around dramatic claims and internet stories.
Scripture's purpose is not to satisfy every modern curiosity about height, bones, or ancient measurements. In David's encounter with Goliath, the larger point is that God was not limited by Israel's apparent weakness. David faced the Philistine in the name of the Lord, rather than trusting weapons or physical strength (1 Samuel 17:45). Read these passages closely, notice what they actually say, and allow the unanswered details to remain unanswered.