Question asks it all xP

Yes, like all wprldgen can be changed with datapack

This may need to be also be changeable in the config too like a setting called "generationChancePerChunk=[DECIMAL #]"

Is that a question? No it can be tweaked with datapakc. Adding a config would be non trivial and redundant

Some people don't know how to make a custom datapack for their game. But thank you for replying and I am sorry

I mean some people don't know how to edit configs. The two don't differ much it's just editing text files. You can read about that in the supplementaries wiki or official Minecraft wiki