XS 160 100A 46
S 165 105A 48
M 170 1 10A 50
L 175 1 15A 52
XL 180 120A 54
XXL 185 125A 56
If you should wear XL according to your height of 7 178cm, but your weight is 80KG, and you say you want to wear something that is not tight, then wear XXL. But it also depends on whether the clothing size is correct or whether the clothing style itself is loose or slim. Generally, if it is loose, you can also try XL size, as long as the shoulders and sleeves intersect with the body when you wear it.
I hope I can help you, thank you! !