Chip antenna design guide
I would not recommend changing the layout of the antenna from the ones shown in the datasheet.

RF antenna design is a very complex subject that require expertise and usually extensive simulation to tune the antenna parameters and meet the transmission standard requirements. Admittedly, it is not my field, but I've seen some approved PCB antenna designs that made me honestly question if they would work at all and how such wierd shape was even conceived.

I suggest you to treat the space occupation of the antenna just like any other specification. If this one does not fit, I would to look for another one instead of trying a reshape that would change and probably kill its performance.