Black Ops 7 is already available everywhere, so the useful question is not whether to preorder. It is whether to try the free trial first, and which platform you should buy it on if you do not already own one.
Already own a PS4, PS5, Xbox One, Xbox Series X|S, or a PC that clears the official requirements? You can already play. Use the free trial first if you have not bought it yet, and only compare new hardware if you do not have a supported platform.
Official store checks
Check these first. Retailer listings can help compare availability, but official pages are the source for platform, edition, and preorder details.
official
Black Ops 7 free trial page
Official trial access covering PC, PlayStation, and Xbox.