Hi,
Indeed externally she will have the same dimensions as all modern 18.000 to 21.000 teu vessels.
The difference will be the depth (holte), i.e. more containers in the holds, and the amount of layers on deck, ie. ten or eleven high or even twelve high for the new OOCL vessels.
Another factor is the position of the forward deckhouse.
OOCL Hong Kong will have imo number 9776171.
Cheers,
Roy