Actually I'd disagree a little.
You will defiantly need a big pot in time, but I would absolutely stick to the bump up method for a few sizes, start with about a one gallon container, once once have poked out the bottom, go up to a 2 or 3 gallon maybe... After that you can move it on up to what're you like.
You end up with a huge plant either way if all goes well, but massive amounts of soil with no roots in it will stay soggier than you like, while the small root zone many get dryer that you might think.
I prefer using small pots for aroids, especially the first year, it forces pups!
Thai giant is surprising sensitive to overwatering when first planting out, fungal infections are common, you can see it, very yellow leaves, stunted grown... A little tug and you find only a bulb with leaves... No root at all or slimy brown ones.
The smaller pot will allow dafter drying, increased watering and more attention. When young and stressed, they can be troublesome.
They really form little to no tuber so there's little reserve of energy if the roots get compromised.
If you grow them semi hydroponically, with a 2-3 gallon pot set up, you can get absuu massive elephant ears in a tiny pot!
Ample water, heat and food, and they have little need for soil!
I've seen Thais like those with 4' leaves, 8' tall with a ten foot spread, in a 2 gallon nursery pot!
Alocasia black stem 7' tall in a 3 gallon tree pot...
Also alocasia portora, with a trunk 8' tall and 4 long leaves growing out of a 5 gallon pot, it was a beast!
