Which also were accounted giants - This is not a fortunate version. The word is not giants, but רפאים Rephaim, the name of a people. It appears that the Emim, the Anakim, and the Rephaim, were probably the same people, called by different names in the different countries where they dwelt; for they appear originally to have been a kind of wandering free-booters, who lived by plunder. (See on Deuteronomy 2:10 (note)). It must be granted, however, that there were several men of this race of extraordinary stature. And hence all gigantic men have been called Rephaim. (See on Genesis 6:4 (note), and Genesis 14:5 (note)). But we well know that fear and public report have often added whole cubits to men's height. It was under this influence that the spies acted, when they brought the disheartening report mentioned Numbers 13:33.

as the Anakims

Deuteronomy 1:28 Where shall we go up? our brothers have discouraged our heart, saying, The people is greater and taller than we...

Deuteronomy 9:2 A people great and tall, the children of the Anakims, whom you know, and of whom you have heard say...

Numbers 13:22,28,33 And they ascended by the south, and came to Hebron; where Ahiman, Sheshai, and Talmai, the children of Anak, were...

The Section Chap. I. -iii.
The question which here above all engages our attention, and requires to be answered, is this: Whether that which is reported in these chapters did, or did not, actually and outwardly take place. The history of the inquiries connected with this question is found most fully in Marckius's "Diatribe de uxore fornicationum," Leyden, 1696, reprinted in the Commentary on the Minor Prophets by the same author. The various views may be divided into three classes. 1. It is maintained by very many interpreters, …
Ernst Wilhelm Hengstenberg—Christology of the Old Testament