a picture would help...

Yes - I can't really follow all of what your depiction is trying to convey. But I do know that 'Green Giant' does make a larger specimen than many people appear to be visualizing when planting it. With a bunch of them planted comparatively close together to form a hedge or screen by themselves being one thing. And mixing in a different kind of plant being another - be sure your hollies have plenty of room between them and the conifers if you don't want them to start getting swallowed at some point.

Height and width: To 60 feet tall with a 12–20 foot spread at
maturity

GrGiant.pmkr (usda.gov)

At that spacing under good conditions and care, location and climate depending, with say a 15gal pot size to start, you are looking at six years to contact of the plant's bottom layers of foliage. At ten years you will have full body contact in the lower six feet with the shading out and die back of the sides in contact.

Long term the spacing all around is too close unless you plan a lifetime of keeping them sheared.