As you can see she was always beautiful. But, let's see her recent photos. 

On the first photo, you can clearly see double eyelid. But, i cannot say it is the effect of plastic surgery (but most likely it is). Her eyes are not that different from before but if you watch this video from Knowing Brothers Episode you will see her double eyelids clearly

. On the other hand, her nose appears to be smaller. Pre-debut Joy had a wider nose, and on these pictures her nose seems thiner. 

Joy also lost a lot of weight so she may look a little different these days. There is no doubt that this girl is very pretty but i am sure she had some work done. Keep in mind this is just my opinion and I am not saying i am 100% correct. If you have opinion, please leave a comment. 

Kpop idol are always looking different with each comeback, so it is hard to say how much work they had done.