>>9695372
Really depends on what kind of cosplay it is.
If it has sleeves or legwear that could be too short if wrongly sized (and look bad), go with one that is closer to your height, probably L/M male or XL female.
You can always make it tighter with safety pins or some sewing, but you won't make it longer. And also never take perfect/just barely fit, because you might gain weight, eat big dinner, and will feel really tight in the clothes, they won't look as good, and the measurements might be inaccurate. Always get yourself 2~5 cm of safety.
For example I'm your height, b/w/h 82/65/84, and I went with one size, small sizes, and M size. I aimed for fit, as most of these clothes are dresses which are not long to the ground, the sleeves aren't meant to be too long either.
On most of these clothes the differences in lengths are also really small, the biggest appearing in the middle blue one, 6 cm sleeve and 9 cm pants between S and XL.
I think there's little need to be worried if you go one size below your height to get a better fit.
But please take my advice with a grain of salt, as I don't have my cosplays yet, so I cannot say how they will fit in reality. It's more of a hint to give you an overview on how particular parts of clothes differ in sizes.
>>9695376
I don't know about other clothing, but you probably meant one letter size bigger (e.g. S -> M, M -> L, L -> XL). I think it's better to look at the measurements, than at the letters, if they are available.