Small hands big chords

[the green piano man]

Hello, I have some problem nowadays with the bartok's dance suite. In the first movement there are a lots of big chords, I barely or cannot reach. I have a small hand, two years ago the 8th was a problem,  today I can reach 9th comfortably, and 10th barely. If I have to play a note in the middle, for example, d a f, it is very hard for me, but I dont think its impossiple. Any exercises to loosen up, or make my hands "bigger"?

[themeandvariation]

yes, your hands should feel supple, loose, but with large stretches - the hand fully extended - you may not be able to feel loose, but at least the wrist can remain supple.  (I am unaware of how to make the hand bigger, as you say.)
There are different options for stretches too difficult. You can roll the chord. With some repertoire, romantic and before, this usually doesn't hurt the musicality , of course it depends on the context of the piece.
With Bartok, rolling a chord where he has not indicated a roll, perhaps will not serve the music, but I would have to see the particular spot you are addressing .
Another option is to drop one of the notes, and that would depend on which note is least needed musically, but of course it would have to be the bottom or top note.
Another option is to have the other hand play one of the notes - if it is able.