How to alter vanilla ore generation and mob drops?

I am making a mod and I want to reduce the frequency of nether gold ore and change the drops of piglins and zombified piglins. I can't seem to figure out how to do so. Is it possible to alter the generation of vanilla ores and drops of vanilla creatures in MCreator?

Preferably, I would like to completely alter the distribution of vanilla ores, both Overworld and Nether, in MCreator. Just curious about how to change properties of vanilla mobs/blocks/items.