Any child(children) can do it.

Hans51What do you native English speakers think?

Only the first is a native expression. The second is a giveaway that you don't know idiomatic English.

Thank you so much as usual and then I am confused because I have seen both expressions like any provocations and any provocation.

In response to any provocations VS. in response to any provocation

And is only one right or is there a difference between them? When can I use any + plurals or singulars?

Thank you so much as usual again!

Your original plural is wrong because the singular is a fixed expression. In your 2nd case, either will work. I suspect that many cases exhibit a preference of varying strength.

Mister Micawbermany cases exhibit a preference of varying strength.

Thank you so much and I have some problem understanding the sentence, especially varying strength, so what does the word strength mean in your sentence?

The correctness of one over the other.

Hans51What do you native English speakers think?

Use a singular countable noun with any when any means (approximately) every. These combinations are usually subjects of sentences.

[Any child / (Every child)] can do it.
__________

Use a plural countable noun with any after a negative verb or in a

Thank you so much! And the reason I was confused was this sentence I asked about before "In response to that, South Korea's defense ministry reiterated that Seoul will strongly respond to any provocations."

This is not a negative sentence and not an interrogative sentence either and then when can I decide to choose any + plurals in a declarative sentence?

Thank you

Hans51This is not a negative sentence and not an interrogative sentence either

Correct.

Hans51then when can I decide to choose any + plurals in a declarative sentence?

I don't know of any rule. One thing you might do is to make yourself a chart of the uses of 'any' that you find, and see if you find any pattern that is cons