I found this sentence in a blog:

I didn't do tell him anything

In the sentence above, I see that do is the adverb.
Is it gramatically correct to write like that where /didn't/, /do/ and the verb /tell/ in one sentence?

Here's one of other examples:
[![enter image description here][1]][1]

It says: .... he really did love .... [1]: https://i.sstatic.net/6FmsG.jpg