You’re raising very important concerns. The tzitz Eliezer mentions the argument against plastic surgery, that it is not healing, but rather saying to Hashem that his handiwork is faulty cv”s. There are also the issues of putting one’s self im danger, injuring one’s self unnecessarily, and vanity/gaavah. Some poskim allow it especially for women if it is to improve their appearance, and this is the position of rav Moshe feinstein in c.m. 2, 66. (though there is a simple distinction between facial defects and internal augmentations, which no teshuvos have been written about, as it involves a severe breach of tznius). Rav shlomo zalman differentiates between surgery removing a very noticeable blemish that causes psychological discomfort and social ostracization, and merely beautification to improve one’s appearance – the former is permitted and the later is not.
Aish.com has a very good article on the topic. However it is not the accepted practice among yereim veshlaymim and bnos yisroel kedoshos, unless there’s a very distinct blemish that will harm one’s ability to find a shidduch/be damaging psychologically/ etc..