Then you will be surely better of by taking the TGV to Lille, where you can change for a direct local train to Kortrijk/Courtrai and Ghent. Change in Courtrai/Kortrijk for Bruges.
Plenty of TGV’s between Paris and Lille, best reserve one quickly. As it’s probably going to be a busy day, with lots of people heading to their family for Christmas. Reservation should be 10 EUR (sometimes 20 EUR per person). You can buy your reservation e.g. here: https://travel.b-europe.com/Eurail-GE/en/booking-tgv#TravelWish
The local train towards Kortrijk & Ghent departs every hour at hh:09, usually from Platform 15 in Lille Flandres. No reservation needed.