Day Trips from Paris

Reims if you love champagne. Versailles is a full day trip to see the whole property.

(Also, do you have a guidebook? There are tons of suggestions already out there and on this forum)

Here are some suggestions from previous posts on this forum to get you started:

https://community.ricksteves.com/travel-forum/france/dat-trips-from-paris

https://community.ricksteves.com/travel-forum/france/day-trips-from-paris-046553bc-5c01-4a32-ab2a-7d65ec2190b9

https://community.ricksteves.com/travel-forum/france/day-trip-from-paris-b090b292-3d39-453f-93a9-35393a1fc5fe

https://www.ricksteves.com/watch-read-listen/read/articles/reims-a-bubbly-day-trip-from-paris

https://www.ricksteves.com/watch-read-listen/read/articles/a-royal-treat-chateau-hopping-near-paris

You get numerous hits with using the search tool on top of the page here.