As only bone will be removed from the outside of the jaw and chin, which will give it a feminine shape, the jaw will be no weaker than the jaw and chin of a genetic woman.
A real severe trauma will be necessary to break it. For sure no reasons to worry.
In case the chin needs to be advanced the chin will be separated from the jaw and fixated with screws in it’s new position. In that case the jaw will be weaker in the midline for a period of about 6 weeks. But the screw fixation is so strong that even in these cases a real trauma will be necessary to make the jaw break.