Num 13:28-33: “Nevertheless the people be strong that dwell in the land, and the cities are walled, and very great: and moreover we saw the children of Anak there. The Amalekites dwell in the land of the south: and the Hittites, and the Jebusites, and the Amorites, dwell in the mountains: and the Canaanites dwell by the sea, and by the coast of Jordan.
And Caleb stilled the people before Moses, and said, “Let us go up at once, and possess it; for we are well able to overcome it”. But the men that went up with him said, “We be not able to go up against the people; for they are stronger than we”.
And they brought up an evil report of the land which they had searched unto the children of Israel, saying, “The land, through which we have gone to search it, is a land that eateth up the inhabitants thereof; and all the people that we saw in it are men of a great stature. And there we saw the giants, the sons of Anak, which come of the giants: and we were in our own sight as grasshoppers, and so we were in their sight”.
This passage does not say that Nephilim were there, only that the spies thought they saw the Nephilim. It is more likely that the spies saw strange and very large, aggressive people in Canaan, larger and more warlike than any they had seen before and in their fear believed them to be the Nephilim.
Jude 6 says, “The angels who did not keep their positions of authority but abandoned their own home—these he has kept in darkness, bound with everlasting chains for judgment on the great Day”. If these were the “sons of God” who mated with the “daughters of men” producing “giants”, the “giants” were destroyed in the flood and the “sons of God” were locked in prison awaiting judgment.