Which surgery? There’s a number of surgeries on a number of areas of the body that trans folk seek out. However, examine why you’re asking in the first place. Are you close enough to the person that you may be a care taker, should they have any surgery? Are you interested in or currently dating them? Or are you allowing your curiosity to objectify their body? If so, take a step back. Trans folk experience enough objectification as it is. Please don’t.