1. reap as one has sown 自食其果
How terribly ill he looks, but he's only reaping as he has sown in youth.
他看起来病得很重, 但这只不过是他年轻时生活放荡结下的恶果。
2. sb deserves it (口)活该,自食其果
自食其果reap as one has sown
我认为这是贬义的啊
所以可以考虑简单翻成: It deserves (him/her) right.
have a taste of one's own medicine
taste one's own medicine.
face the music