Paris with 16 yr old in August

Just in front of Notre Dame, is a virtual reality experience called Eternelle Notre Dame that I bet your 16-yr old would love. Make sure you purchase tickets for the one at Notre Dame and not at La Défense. It enacts the building of Notre Dame from its inception up to the fire. Really, really cool.

And btw, the entrance is a bit tricky to find. I didn't find it signed particularly well. It's in the northwest corner of the parvis, down some steps.

We enjoyed a a perfume making class at Fragonard's perfume museum - in English.If you are interested, I would pre-book. Small groups and they do sell out. https://musee-parfum-paris.fragonard.com/en/

Yes--definitely do Eternelle Notre Dame. We (two adults and one adult child) did this VR experience in June, and it was a blast! We all came away smiling and laughing. Although I did have to lift up my goggles so that I could see just a sliver of the floor so that I didn't fall down. Anyone in your party who has balance/mobility/vertigo issues maybe should skip it. I joked that I would have liked to use my mom's walker to hold onto! Book ahead online as it does sell out. Find the entrance beforehand. As the other poster mentioned, it's tucked in the corner opposite ND. There were tall signs when we were there, but I'm glad we found it ahead of time because our RER train was delayed returning from Versailles and we had to run to get there on time. I'm glad we knew where we were going.

Humn... some added thoughts -

Galerie Dior is the museum of the haute couture house of Dior.If she is interested in fashion and the dress styles and Dior, then Yes, it's absolutely worth visiting! .
Get tickets in advance. (there is also a Saint Laurent Museum but it is temporarily closed).

And - I think that there is a special exhibit on Worth at the Petit Palais through September.

And another - The Grand Mosque of Paris has a hamam open to the public and its fascinating - beautiful building, wonderful massages and other treatments and nice tea room. Check the days because some are for women and some for men. Really different., fascinating experience.

Louvre Coutre exhibit in the Napoleon III apartments?

Louvre Coutre exhibit in the Napoleon III apartments

When I was there, it was very popular with teenagers and young adult girls. They huddled around each dress, all excited and taking pictures.

The Louvre Couture thing has 100 items mostly dresses -- we did it in two trips and it ends in the Napoleon apartments which are a treat in themselves. i had not visited them in 20 years and had forgotten how magnificent they are.

The basement level exhibits of the Hammurabi code as well as the replicas of the Asyrian Gates was a big hit with my 14 year old grandchild and this kid also loved the Egypt exhibits.

See if you can book something at the Garnier for the building. Mostly it is ballets there now but I actually found a free noon concert which I booked many weeks in advance.

If the Musee des Arts Forains is bookable she might enjoy that:
When I did this long long ago it was VERY hard to get in; after many years of trying I finally got places on a French tour for our group of 4 only one of whom spoke enough French to really be able to follow. It was still wonderful. I think in recent times it has become more available.

https://janettravels.wordpress.com/2012/12/31/magic-at-musee-des-arts-forains/

I'd also recommend a trip to St. Denis on the 13 metro, stop Basilique St. Denis. My daughter joined us for a week on our recent trip and we could not get into Notre Dame (our tickets were cancelled with the death of the Pope) so we took her to St. Denis the oldest gothic church in Europe. It houses the Tombs of the kings of France -- very memorable
She loved it and we really enjoyed the day. I think it is the most overlooked awesome site in Paris.
https://janettravels.wordpress.com/2010/10/26/confronting-mortality-at-st-denis/
These are snapshots from a trip 15 years ago -- things are a little more regimented now with railings keeping people from getting as close to the tombs but it is still an amazing thing to see. We got lunch on the town square outside and then walked to the Legion of Honour park and from there to a different metro stop to get back to Paris. A wonderful day.

It kind of depends on what type of fashion she likes (not an area that I'm knowledgeable about). You could walk along the streets of haute couture stores (I think Rue du Faubourg Saint-Honoré?) Paris seems to me to have many more non-chain stores than I see on the streets of cities in the U.S., you could visit those with her, and she could have the store person help her purchase some clothes (or makeup). My adult daughter has been involved in the fashion industry, and visited several curated vintage fashion stores when she was in Paris earlier this year. I've seen some of her purchases from there, and they are beautiful.

Theater, obviously more difficult unless you all speak French.

People-watching, find a cafe and spend a couple of hours enjoying the people-watching views.

For Haute Couture window shopping Avenue Montaigne and George V area have lots of fashion houses with avant garde 'editorial' pieces in their windows. Maybe someone who has that interest could narrow it down more -- we have walked through that area when going to theater and there was some amazing stuff in windows.

My 16 year old daughter is looking forward to returning to the thrift stores in the Maris this August - there are a ton, just use google maps, but Kilo Store is good place to begin. She was last there when she was 13 and came back with quite the haul. For “theatre”, we have tickets to Paradis Latin (similar to Moulan Rouge) if you feel comfortable with cabaret.

Another vote for Dior museum. https://www.galeriedior.com/en

Fragonard Perfume Workshop is nicely done - you make your own and learn about perfume making. Edit - oops, anther second vote!
https://musee-parfum-paris.fragonard.com/en/perfume-creators/

Take a look online at sites like Paris Time Out. There are often temporary fashion exhibits at various venues. I've seen numerous of these temporary exhibits - always good. Maybe there is something in this article: https://www.sortiraparis.com/en/what-to-visit-in-paris/exhibit-museum/guides/207610-fashion-exhibitions-couture-events-to-discover-in-paris