can "do" use for emphasise not just before a verb?

Question

The sentences below are written in "introduction to Linux Mint"

"Finally, software which is distributed in this way is often, by virtue of necessity, “static”. This means that not only do you need to download the program itself, but also all of the data libraries that are required for it to run."

I know "do" can be used for emphasis before a verb, but I wonder if it can be used for emphasis as the way mentioned. If "do" is not used for emphasis in that text, what it can mean? There is no question mark in the text.

Answer 1

Following an adverb with "negative" meaning, the subject and verb become inverted. The inversion similar to that which makes a question, but the sense is indicative. For example:

Never have I seen such beautiful thing. (= I have never seen such a beautiful thing)

To form an inversion of the simple present of a verb (except be) the verb do is used, exactly as if you were forming a question. The simple present and past uses "do" or "did".

Rarely do you visit me. (= "You rarely visit me")

The adverb receives stress. The effect is quite formal and a little unusual, but the emphasis is on the adverb. The word "do" doesn't emphasis "you", or "visit"

The "not only ..." is a negative adverb form, so it takes this inversion.

Not only do I play tennis, but I play football too.

The meaning of your sentence is that both the software, and its library must be downloaded.