I used to grow pumpkins but no longer. To insure a big one you'll need to protect the vines from the Squash Vine Borers and Squash Bugs which can kill and/or sap the plants energy. Powdery Mildew is another potential plant killer over time. As for the pumpkin, try to hand pollinate it for complete pollination and remove other pumpkins that grow on the same vine. No doubt there are lots of other tricks the "professionals" use to win contests like growing Atlantic Giants variety. Big Max can get big but 100lbs? Maybe.

Lots online.

https://ohioline.osu.edu/factsheet/hyg-1646

https://modernfarmer.com/2015/10/how-to-grow-a-giant-pumpkin/

hubby was a professional pumpkin carver, so we were in contact with many pumpkin growers. We only tried growing giant pumpkins one time and got several in the 300lb range. You do have to start with seeds from a giant pumpkin! Not the regular jack-o-lantern type.

First of all. clear a LARGE area. Mix in a lot of composted stuff and break up the soil. We had a good amount of aged goat manure on hand.

If you start your seeds indoors or in a greenhouse, look for the 3rd leaf that emerges and that is the direction your vine is going to travel. Plant accordingly.

We had a watering system that we could water all of the plants with the turn of a faucet. Your pumpkins will want a LOT of water!

I'm not sure where you're located, but you might want to find a pumpkin patch to get more info.

Have fun!