Perfumery

If by perfumery, you mean a perfume store, try a Nose on Rue Bachaumont in the 2nd arrondissement. I was not sure what a perfumery is so I looked up the definition of and my dictionary says a place where perfume is made or sold and I am not sure which you mean. Nose is a lovely shop but you do not help yourself. You describe what scents you like and you are presented with various fragrances. The guy who looks like Bradley Cooper is very good at matching what you say you want to fragrances. I also like Ex Nihilo on Rue St Honore in the 1st (sort of near Place Vendome). But really, my daughter jokes that old churches and perfume shops are Paris’s Starbucks — one on every corner.
You may find this https://www.tripsavvy.com/top-perfume-shops-in-paris-1618851 interesting. I have been to most of these stores and found them quite charming. Perfumes (and handbags and shoes) are my weakness.

I don't know what you mean by a "must buy perfume". Chanel No. 5 is the most popular, according to the industry standards.
I would suggest you go here, then figure out what you like the most:
www.cntraveler.com/story/a-sneak-peek-at-pariss-new-grand-musee-du-parfum

The big perfume showrooms, museum (a little), and blending area for perfumes you can take away are in the south of the country, in Grasse west of Nice (where a lot is made), and in Nice (much more sales), and in Eze le Village just east of Nice.

I don't know of anything comparable in Paris.

The essential oils are made where the flowers are grown - in the south east.

When in Paris a few years ago, I sought out a Fragonard Boutique, the St. Germaine location, I believe. I was pursuing the Violette fragrance. Google Fragonard locations Paris and you will see one location called Musee de Parfum.

I enjoyed visiting the boutique and finding just what I was looking for.

I quite like Fragonard---as mentioned above. There's several locations in Paris and I always make it a point to make a stop there. While they do have a website available to American customers, they don't offer all of their selections on there. Plus it's a lot cheaper to pick it up in France. The location near the Opera (about a 2 minute walk from the Opera) has their own museum. Their parfumes are of excellent quality and the packagings are very well done.

As Debbie and Alexander point out, the Musee de Parfum at Fragonard is worthwhile, imo. It's near Opera Garnier-Galleries Lafayette.

https://musee-parfum-paris.fragonard.com/en/

There are also "ateliers du parfum" which let you make your own.
Nicolai, Les Fees du Parfum, on and on - in the 3rd and 4th arrondissements.
I don't think they hold a candle to Fragonard, until you know what you like.

You might also try on (free) spritzes of parfum in department stores, like Galeries Lafayette and BHV and Printemps.

I too.... bought purchased from Fragonard. It was back in 2006. I remember the one I went to was by the Opera house somewhere. Google them!

If you are in the square of Place des Vosges, look for a small perfume shop which is about five doors from Victor Hugo’s residence. I cannot recall the name of the shop but it is very charming and, unlike some of the shops which are focused on (as they must I suppose) marketing. The owner/operator of the shop in Place des Vosges was generous with his time explaining how he created the scents and, there were interesting displays and artifacts throughout. Very special.

I also like the Fragonard shops. I have bought perfume there twice now, and always get compliments on it here at home.
The first trip there it took me two weeks to test and smell every one they made, as I was looking for one that had been given to me as a sample a few years before, and had no name for it.
I finally found it at the airport Fragonard shop on the way home.
This year, I made sure to stock up!
It’s called “Fragonard”, by Fragonard; I think it’s their original fragrance from their early days.
The shops are pretty inside, too, even if you don’t buy anything.

A word of warning: Some years ago, my wife and I visited Fragonard near Nice. We had to check our bag, and the perfume that my wife spent hours selecting was removed from our luggage. Small, easily disposable, easily sold to others - it might be a sensible idea to ship the perfume home from the store directly.

I also recommend getting on Fragonard's mailing list. They send out samples and also occasionally have deals online.

The perfume shop in the Place des Vosges is Parfums et Senteurs du Pays Basque. I have a lovely bottle that I bought on my last trip.

Do not forget Lafayette Galleries. They have a huge selection, as does Printemps Haussmann.