Checking to see if there are high speed trains from Charles de Gaulle Airport to Reims.
Check on www.rome2rio.com. com
The answer is yes. You can check on the official site of the train service: https://www.sncf-connect.com/. Also, please note that the TGV station for Reims when traveling from CDG is Champagne-Ardenne TGV, which is about 8 kilometers from Reims. You can take a local train from the TGV station into Reims.
My wife and I took this train last summer upon our arrival at CDG. Very easy and convenient. Enjoyed 3 days in Reims before starting RS tour in Chartres.
I'd go to Paris and take the TGV there which puts you right in downtown Reims with no need to make a further transfer on arrival as you do with the one from CDG. I think the train station is Est -- but when you book it will let you know.