You cannot choose to grow large dias vs weight, just big. The two are pretty much the same for a given variety as mass is proportional to volume.
As to growing them, every showman in the world has their own secret extra-go ingredients but ultimately these will only add the few additional kilos that may or may not take the prize.
Generally, to get a super specimen requires good timing with the seed germination such that the plant will grow from day 1 without any check. Extremely fertile soil along with a good sunny situation sheltered from wind and passing animals is vital. Ideally, you also need to save your own seed from a large specimen in order to use the very largest seeds. The bigger the seed, the bigger the cotyledons, the more vigorous the plant, the bigger the pumpkin.
Pumpkins should just about be setting now and as soon as you are confident a few have set, select the best placed one then ruthlessly remove all other embrios. Remove all flowerbuds too.
Wishing you all the best for this year, but I may be the opposition next year.