Were there giants in Canaan?

Answer

You can rest assured, on the evidence of archaeologists and others, that there never were giants in Canaan. However, the Book of Numbers contains two different, conflated accounts of the twelve spies sent into Canaan. In one account, known as the Yahwist account (Numbers 13:28), the spies returned and stated that there were some giants among the inhabitants. In the Priestly account (32-33) the spies stated that Canaan was an unconquerable land that devours its inhabitants and that all the people they saw were giants. The discrepancies should be enough to alert the reader that these were not historical accounts.

Another view:

Anakim, a race of people of extraordinary size, lived in the mountainous and coastal regions of Canaan . Three are mentioned in the Bible: Ahiman, Sheshai, and Talmai, who resided at Hebron. (Numbers 13:22)
The 12 Hebrew spies first saw them there and 10 of the spies gave a frightening report of the experience, claiming that these men were Nephilim. (Numbers 13:28-33; Deuteronomy 1:28) Large men of the Emim and the Rephaim were likened to them.
(Deuteronomy 2:10, 11, 20, 21; 9:1-3)"... a people great and tall, the sons of An′a‧kim, about whom you yourself have known and you yourself have heard it said, 'Who can make a firm stand before the sons of A′nak?"
(1 Chronicles 20:4-6) "...a man of extraordinary size whose fingers and toes were in sixes, twenty-four; and he, too, had been born to the Rephaim."
(Joshua 11:21, 22)Joshua destroyed the Anakim of Canaan, in..." the mountainous region, from He′bron, from De′bir, from A′nab and from all the mountainous region of Judah and from all the mountainous region of Israel. Along with their cities Joshua devoted them to destruction. No An′a‧kim were left in the land of the sons of Israel. It was only in (the Philistine cities of)Ga′za, in Gath and in Ash′dod that they remained. "