How to add emissive textures to the ores ?

What do you mean? That depends on how you are adding them in general. Ores like redstone ore - which aren't truly emissive but just have a light level - should just work out of the box. In terms of other stuff - that depends on what tool you're using to add emissive textures, which Minecraft does not have for blocks by default.

Like this here : https://www.planetminecraft.com/texture-pack/bare-bones-emissive/

in _e format

That uses optifine's special system, not a built in feature of Minecraft; Excavated Variants does not currently have any special support for it. You would have to manually add emissive textures for the blocks yourself

Yes I know but how if there are no textures in both mods (dynamic asset generator and ExcavatedVariants)

The mods generate the textures at runtime. They're still there, just not in the jar

Where do you have a file path or something ?

You can enable caching to see where they are placed