Your boyfriend 180, weighs about 120 kg. The size of the clothes he wears depends on the brand, because there is no standard size. Even the clothes of the same brand, the same size and different payment may have obvious size differences, so I can only recommend you a relatively reasonable clothes size according to the relatively standard international brands.

Generally speaking, the recommended height and weight of the brand relative to the standard male figure are as follows:

S code: suitable for men with weight 100- 120kg and height 165- 175cm.

M code: suitable for men with weight 120- 140 kg and height 165- 180cm.

L code: suitable for men with weight 140- 160 kg and height 170- 185cm.

XL code: suitable for men with weight 160- 180 kg and height 175- 185cm.

XXL code: suitable for male weight 180-200 kg, height 180- 190cm.

According to the above standards, your boyfriend will fit in size S, but it will be shorter and size M will be slightly larger, but the length of the clothes will be more suitable.

Remember, this is just the height and weight that big brands are suitable for relative standard clothes sizes. Some domestic 6XL products are not as big as the L size of famous brands, so there is no real specific standard.