Different UV's for each channel of a texture

Have a texture I’m keeping a few masks in.

I want different UV scales for each channel- how can I do this and is this a bad thing to do?

That’s fine, it just uses more memory for the storage of the UV channels. You can have multiple UV channels and to use them you in your material just use a TextureCoordinate node to set a channel for a texture and then plug that into the UV node on the texture.

Ok, I’m not talking about map channels on a mesh, I want different scaling for RGBA texture channels. I still use a Texture Coordinate for that? Is the index number what channel it’s changing? 0 all, 1 Red, 2 Green, etc.?

Same thing, TextureCoordinate can be used to change the UV channel or control texture tiling
UV channels are a set of texture coordinates for a mesh, so for instance you might have a UV channel that allows you to pan a texture from the top of an object down or something like that.
To change it specifically per channel, you would have to have copies of the texture with the different tiling applied to each, you would then just use whatever color channel output that you want from the texture, if you need to recombine them into a single output you can do that too, the material editor is very flexible.