"To shorten the legs" is an expression that means to reduce the length or duration of something. It suggests that the legs, which typically support and add length to an object, are being made shorter to make it smaller or quicker.
Sentences with «to shorten the legs»
However, black ankle strap sandals can often visually shorten your legs. (fashion-landscape.com)
After all boyfriend jeans shorten my legs too and I love them. (40plusstyle.com)
Straight - legged or wider - legged jeans shorten your leg line when rolled. (babble.com)