Does chess really make you intelligent

Hopefully Sanjay will give more info about the tests and low marks.
As to chess 'making you more intelligent' - that's 'nebulous'.
Chess and other sports may be useful in determining what one is Not doing.
And on the internet - chess means you're interacting.
Not just with people.  It also means you're interacting anyway.
Whereas with Netflix or a book - kind of passive.

Yes, interaction is important.

https://www.chess.com/blog/Casiochess/does-playing-chess-make-you-smarter#:~:text=Chess%20improves%20IQ.%20According%20to%20a%20study%20conducted,Education%20student%20at%20the%20Flinders%20University%20in%20Australia.

copy and paste it

If you ask me it is hard to be smart if you don’t have a brain…

      A matter of semantics. If what the OP means by "intelligence" is the innate capabilities that IQ tests measure, then the answer is no. If what the OP means by "intelligence" is becoming more adept and organized in applying one's raw intellect to specific problems or becoming better at systematically acquiring knowledge, the answer is maybe. Someone who is already competent in these areas is unlikely to gain much by playing chess. Less developed persons, particularly the young and disorganized, can benefit greatly by acquiring and understanding techniques of study, analyzing and applying knowledge.

The idea of having options - and selecting better ones ...  that's kind of emphasized in chess - putting it mildly.
Does that idea of comparing options 'get away' from people quite a bit ?
Putting it mildly - Yes.
Intelligence could be defined in many ways.
There's actually several phases to it.  Is 'option selection' at the core ?
Not necessarily.
Perception-objectivity-evaluation-assignment of priorities-comparisons of options-consulting with one's own experiences and past observations-obtaining more information-ability to function on these and other points and to select and  execute (or refrain) in uncomfortable - novel-unfamiliar- and unexpected situations under pressure in a practical amount of time or with timing.  Assigning investment of time ...  
Building more experience and learning from same ...  as opposed to 'option selection'.
And what about creative intelligence ?  and other forms?

Defining intelligence is simple?  I don't think so.
It can get tough defining what money really is too.

Why?  Because there are competing definitions.

Syllogisms don't define intelligence. 
Nor is the dictionary a bible - except for those that want it to be.
Nor is simplicity necessarily accurate.
And - people will have their own definitions.

Will playing chess sometimes lead to situations where you find yourself then getting better results on other things outside of chess?
Try ...  sometimes.  Things aren't always what they seem to be.

Any new perspective could/can often be helpful.
You take a two week tourist vacation from your job and go to another country ...  you come back refreshed and with a new take.
Suddenly - issues that were difficult before ...  get quickly overcome and left behind.  

And you realize that which used to be of importance to you never should have perhaps. Yes, a fresh, new perspective is always of benefit. 

That too.  Or instead.  Mis-assigned priorities.

Lots to talk about under the forum topic.
I remember from 30 years ago - somebody asked me ...  and I showed him some chess basics.  That's happened many times - but this one stood out.
I showed him some basics - especially about King and pawn versus King and also that but with a rook thrown in for each side.
But if I had that one to do over it would have been more like:

"Distinguish observations from calculations.
If you go ahead and compare sequences of future moves - without first determining the options available properly - and without enough early 'tactics detection' - then that's not good for results. "
And:  "Why is observation often deficient?  Because of misdirection.  Misdirection from the chess pieces and position - not from the opponent."

Translation:  many games are lost because somebody didn't realize a move was available.  On move.   Right there now.  
Does that have a cousin outside of chess ?  Definitely  !   

no not really

Trying to narrow down the options or methods -
constriction or isolation - leading to false premises - leading in turn to whoever attacking his own false premises.
Is such a thing 'intelligent'?  Maybe.  If it 'gets power'.

There's something called 'compulsion to relieve cognitive disonnance'.
Referring to a terrible (but counterproductive and non-necessary) need to resolve a 'conflict between two internal cognitions'.  (within the same mind)
Whoever - wants a 'winner'.  Refuses to accomodate two conflicting internal cognitions  ....  paradox is abhorred. 
And controversy (as oppopsed to internal paradox) is to be 'us versus them'.
Result:  one cognition is rejected. 
The one that's protected is often the time-honored one.
Is this 'intelligent' ?
Usually - all the 'intelligence' is invested in maneouvers to justify the time-honored or 'personal' position.  
Logic - reality - and better results all go out the window.

Irony:  when these behaviours are discussed then the behaviours happen ...  is what usually happens.  Not the discussions of them.

And people can 'dichotomize' into 'clever and unclever' too.
And other digital 'A and B'.  
Many invalid generalizations can be made. 
And much projection of projection.

Getting back to the main forum topic ...
could anything  'make somebody intelligent' ?
Well - birth could.
That one's easy to misinterpret though.
Misconception:  "Ah I see - you're suggesting people are born stupid or smart !"
No.
People are born with the most complicated thing in the known universe.  
Brain.  It has trillions of grey cells.  

Regarding 'modifying the degree of intelligence'
If somebody has a very great pain - physically ... or something is very distressing ...  and then that pain or distress is relieved ... completely taken away ... will concentration and focus and attention improve?  Thinking?
Its meant as a rhetorical question.

For those who wish to hold that degree of intelligence is fixed in every individual - in every dimension -  then such persons are likely to stay with that.
Very narrow and limited:  confusing 'intelligence' with 'ability' to be intelligent.  Another one-dimensional unreality.
Is 'intelligence' A or B and on a very short one-dimensional line ? 
For those who want to see it that way - for whatever motivation.
There's an irony there though.  

just eat more fiber. easier.

If you play slow chess, no books, no puzzles, no videos, it will improve your focus. problem solving and creativity.

I wouldn't say that chess makes you more intelligent, but for me at least, it helps to keep my mind sharp and working! And that's what I love about it!

Three great players didn't appear to be 'hurt' by chess.
Namely - Lasker - Euwe - Bottvinnik.
But for two great players - did chess appear to help them with their 'problem'?  Apparently Not.  Putting it mildly!
Yes I'm going to name them.  Morphy.  Fischer.