You tell the doctor your symptoms, he explores you and perform any tests considered appropriate, and the doctor decides the prescription.
But you might have prior experience and preference.
A friend of mine always asks "Hey, can you bring antibiotics back?" when I go on vacation somewhere where access is easier.
Doctors here will give you a hard time if you want it.
I think that's how it should be. But sometimes you know you need antibiotics.
You tell the doctor your symptoms, he explores you and perform any tests considered appropriate, and the doctor decides the prescription.