First time in Paris

You could easily spend the entire time in Paris and not run out of fascinating things to see and do. However, you've already said you want to go to Versailles and Normandy. A day trip to Normandy will be a very long day, and you won't have many hours on the ground in Normandy as you'll be traveling most of the time just to get there and back. You might want to sign up for a bus tour that takes you directly from Paris, includes a guide for the significant sights at the Normandy beaches, and brings you back in the evening. See, for example:

https://worldguidestotravel.com/best-normandy-tours-from-paris/

A day trip to Versailles is much easier and you can do it on your own by train. With those two I wouldn't do any other day trips -- take advantage of being in Paris for the few days you have remaining.

I really don't think a day trip to Normandy is a good idea. There's too much time spent in transit. But if you absolutely must do it, I think the best option is the Overlord Tour designed specifically for people who are staying in Paris. You take the train up to Bayeux and are met at the train station at 9:30 AM. (Their tours for people staying in or near Bayeux start a bit earlier.) At the end of the full-day tour, you are dropped off back at the station at 6 PM to return to Paris by train. I believe the train will get you to Bayeux a bit faster than a tour bus, and it will be more comfortable. Equally important: This tour is a full-day tour, because you travel on your own to and from Paris outside the tour hours. If you sign up for a D-Day bus tour from Paris, I think you'll find you don't actually reach Normandy until considerably later than 9:30 AM, and the Normandy sightseeing will end earlier than the Overlord tour does, because the bus company will use some of the day to drive you back to Paris.

Here's some information on the Overlord tour I'm describing: https://www.overlordtour.com/product/tour-2fs-omaha-utah-full-day-tour-week-days-only/

You can check train schedules from Paris to Bayeux on the SNCF website: https://www.sncf-connect.com/en-en/

One reason I discourage day trips to Normandy is that there are so many other worthwhile things to see there besides the invasion sights that can be squeezed into a one-day tour. The town of Bayeux was spared wartime damage. In that one town alone, you have the Bayeux Tapestry, a lovely cathedral, a pretty historic district, a modern invasion museum and the British War Cemetery. The tourist office offers a walking tour, too.

You are talking about 3 day trips here. That doesn’t leave much time for Paris itself. If the Champagne region is the most important research some tour companies that will pick you up in Paris and take you for a day trip and bring you back. If it were me I would skip Normandy this time, and just plan for that for the future. It’s better to spend more time in that area. As noted, Versailles is an easy day trip by train DYI. Then pick your top sites in Paris and plan the rest of your days around those.

Another vote against Normandy! It's just too far for a day trip. Champagne is closer.

If you land at CDG grab a car and drive to Champagne and spend the night. Then return to Paris for the remainder of the trip including one morning at Versailles.

I'd definitely skip Normandy until you can give it more time than a day trip from Paris which, in my mind, is just too much travel time. Do a day trip to Versailles and to visit the champagne region and then spend the rest of the time in Paris. Personally I wouldn't give up a day in Paris for champagne, but it's your trip and if it's a must for you then go for it.

If you’re flying from the US, I disagree with renting a car after being awake all night. I would buy Rick Steves Paris guidebook 23rd edition and take a self-guided walking tour each day and you’ll have no need to sleep outside of Paris. Day trips are fine but I would make Paris my home for five nights. This way you can exhaust your time there and when you return to FR visit Normandy, etc. then.

If you arrive on Monday, that's jetlag/get settled day.
Then you only have four whole days until you leave on the Saturday.
I don't know how you could possibly fit in all those daytrips.

Considering you only have four actual full days in Paris, I don't think all these day trips plus "soaking in" Paris are possible.