Possible to "copy" another text style into an existing one in the same document?

Let's say I have a document with a style called "Giant Cool Heading" and another style called "Style 1".

Style 1 has already been set up with color, size, underline, etc.

Is there a way I can somehow, within the same document, tell "Giant Cool Heading" to "copy" all the settings within "Style 1" ?

I realize I can delete Giant Cool Heading, replace it with Style 1, then rename it, but wondering if it can be done the way I described.

thanks