Working on Modded Resource Pack

I'm trying to create a resource pack where I can change the custom model data for a modded item. I keep trying to do it, and it's just not working, pls help

I think I need to find the Item Model Definition from the mod, and I just can't find it. Here is the github link to the code!

https://github.com/AcoYTMC/Corincadabra-1.21.5

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