Generally, I use something like 54x29x8, at a minimum. Leave the rear wheel on and secure the front wheel against a cushioned bike.
It works best to completely remove the stem/bar, while disengaging the cables. Makes more work for assembly, while reducing risk of scratches.
Nowadays, the larger and sturdier boxes from electric bikes work noticeably better. It adds some weight and girth, however.
You might fit a typical bike in 36x30, but it will require two boxes by packaging the wheels separately.