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This is something that can't be done just by changing some variables. (Well... actually... it could but you would need to change more than 500 values, and nobody got time for that)
So the easier step is to edit the datapack. You will need to know what a block tag is though. If you don't know that, you might want to read the wiki entry about them. You'll also need a Text Editor, like Notepad++, Sublime or Visual Studio Code. Then you need to unzip the datapack. The Software WinRAR or 7zip can do that. The filestructure can be seen in the following and the folder you'll want to have open is the one for Blocktags.
This here is the folder structure. You can see the filepath towards the block tags:
The important Ones are highlighted in red. These .json-files control what the individual tools can vein mine.
When you want to limit it to ores only, then you need to edit the tags for the tiers of pickaxes. The Pickaxes are divided into their tiers because a wooden pickaxe can only mine coal, nether quartz and nether gold ore. Then the next tier can mine anything the previous tier can plus iron and lapis ore. And so on. So If you want to limit veinmining to all ores only you have to edit the files "wood_pick.json", "stone_pick.json", "iron_pick.json" and "dia_pick.json" to look like this:
I'd like to point out the Importance of the last entry in this list, or if it's the only entry in the list: There can't be a comma after that, otherwise the Block tag will be an invalid json-file and the datapack can't work. You see I didn't put a comma behind "minecraft:ancient_debris". That's how it should be, otherwise it won't work.
Then save the file and zip the datapack back up again so that the folder structure is the same as in the first picture. And that's all there is to it. I hope that helped so that you can customise this datapack to how you like to have it.