How do I create a custom product attribute template?

I have a bunch of attributes

Brands
Color
Size
etc
etc
etc

I’ve already created all the products and I’d like to add these new attributes to all the products that have already been created without going through them one at a time.

I could create the terms but from bulk editor does not seem to apply the terms if the product itself does not already have these attributes assigned to it.

Please assist!