When you posted this on English Stackexchange you indicated that this is a question from an exam and that the test creators believe the correct answer is "true" while most of the students believe it is "false". The two sides are disputing the meaning of "hardly any".
The dispute about the meaning of "hardly" is not the only problem with this question. It also contains two grammatical errors which change the meaning in surprising ways. To keep things simple, I will consider these one at a time.
What "Hardly" Means
The sentence does not say "hardly any", but let us pretend for a moment that it does, like this:
Hardly any other artist of his time created as many works.
Here "hardly" means "with difficulty" (Merriam Webster https://www.merriam-webster.com/dictionary/hardly).
It refers to a position on a question which is difficult to maintain. Look how it is used in this dialog:
John: Who ate all the potato chips?
Sam: I didn't eat them all.
John: But there are hardly any left!
Sam has eaten almost all of the potato chips. The few small pieces and crumbs which he has left at the bottom of the bag are not a proper portion. It is "hard" or difficult to maintain the position that he has left "any" for John.
So there may be very few artists who created as many works as Picasso. They may not be well known. They may not be very good artists. All these things make identifying them "hard". People may argue with you about it. But "hardly any" does not mean none.
So whence comes the idea that "hardly" means "not at all"? To get there we start with a sentence like this:
You can hardly suppose that I would eat potato chips.
The speaker is asserting that it is well known that he does not eat potato chips at all. Thus it would be "hard" for someone to think that he would. This is frequently shortened to:
I would hardly eat potato chips.
It now seems as if "hardly" means "probably not" or even "certainly not". Such definitions can be found in dictionaries, but not as the first meaning. But this meaning only applies to matters of opinion, to what can be "supposed" to be true or false. It does not apply to questions of quantity.
In questions of quantity, time, or measurement "hardly" means "with very little room to spare". For example:
There was hardly a person on the street. (very few)
There was hardly enough to eat. (just enough to survive or not to be hungry)
I had hardly finished the test when the bell rang. (almost no time to spare)
The verb "create" should have been put in the simple past tense, "created". The narrator is trying to make a simple statement about what Picasso accomplished during his lifetime. He is not telling a story.
The narrator has mistakenly used "had created" which is the past perfect. The past perfect is used when telling stories in order to describe a sequence of events. For example:
I had graduated from university only two weeks ago when I got my first job.
First the narrator takes us to a date two weeks after the completion of his education. This creates a certain context and expectation in our minds. That he found work is now natural and expected.
Now consider this sentence (which is not in the test):
Hardly any other artist of his time had created as many works.
This takes us to a time in Picasso's life when there were very few artists who had created so many works. We will be wanting to know what happened next.
I do not think the author of the test intended the implications of using the past perfect tense.
But that is not the end of our difficulties with this sentence. The author has not written "hardly any other artists had created". He has written "hardly had any other artist...created". The modifier "hardly" has been mistakenly attached to the verb instead of "other artist".
As a result, the sentence asks us to consider what happened immediately after each time when any other artist created as many works as Picasso. After setting up this situation the sentence just breaks off without telling us how Picasso responded. Were were expecting something like this:
Hardly had any other artist of his time created as many works than Picasso would quickly paint 100 more to get ahead again.
I do not think this is the sort of idea the writer intended to convey.
The writer probably intended to say:
No other artist of his time came close to creating as many works.
But the sentence he actually wrote contains three separate errors. These errors change the meaning in ways he did not expect. The word "hardly" does not refer to the number of other artists at all. Instead it refers to how soon the response came when another artists exceeded Picasso's record. It then breaks off without completing the thought. It is a sentence fragment.
If the word "had" were removed from both places in the test question, then "hardly" would become attached to "any other artist of his time". But because this would be a how-many construction, "hardly" would mean "very few", not "not at all" as it would in a could-one-think construction.
Since the second sentence is garbled, it is not appropriate to grade students on their answers to this question. It should be ignored when scoring the test.