Does a flat nasal bridge and wide set eyes always mean a chromosome disorder?

No. Sometimes this is a normal inherited trait. Try to see if others in the family share that trait. If you suspect that this person has a chromosome disorder, the doctors that diagnose them are called genetecists. If the person is your child it's best to see a pediatrician about your concerns first. (of course, if this is a coworker or the like, it's best to just leave it be ;).