Ah, you see it is not so much about etiquette, more about the ritual of being served by the chef as he/she hands you the food. The conversation is part of the pleasure. You will almost certainly hear an explanation of where the food came from, how it was seasoned or aged or prepared, and you can reply with your thoughts on that particular fish, comment on the taste, ask further questions, they always love people who are interested in food, especially theirs--or you could branch off to talk about just about anything, like the difference between now and before the pandemic, about where you grew up and how you came to be doing what you are doing. . .it really doesn't matter, but at the end, if you decide you like each other, for whatever reasons, you will be invited to return, or you will offer to return, but this is the beginning of a relationship where you may receive priority in reservations, and be offered little dishes they don't have enough of to offer to the other customers who are paying the same money. There are exceptions, but someone who chooses to serve people individually over a counter love to talk, like many old-time bartenders.