Learn English – Is “how you do you” grammatical

The basic (declarative) sentence is:

He does not know.

You can turn this into an interrogative clause with subject-auxiliary inversion. Just switch he and does:

Does he not know?

You can optionally replace does not with doesn't in the original sentence, using the suffix -n't rather than the word not:

He doesn't know.

Now the auxiliary is the single word doesn't, so if we apply subject-auxiliary inversion, we get:

Doesn't he know?

Lastly, you can turn the original sentence into a question by using rising intonation at the end, which you indicate in writing by replacing the period . with a question mark ?:

He does not know?

However, this is only appropriate in certain situations, for example as an echo question—repeating what you heard as a question to express incredulity or to confirm that you heard the speaker correctly. Most (but not all) situations where this would be appropriate are informal, and as a result "He does not know?" sounds somewhat unusual. Instead, you can use the contracted form:

He doesn't know?

But most of the time the interrogative form is more appropriate.

Yes, you have it right.

The idiom essentially translates like:

He is quite fast. Would you say he isn't?

or, otherwises, an implied "challenge" to the recipient of the question to say otherwise.

So, like the examples you have written, you'll want to add/or remove an auxiliary verb (for these contractions, the not, or 'nt) when asking the question, to make the verb "opposite."