Generally TGV INOUI tickets are refundable/exchangeable free of charge up to 7 days prior to departure else a 19eur charge applies: https://www.sncf-connect.com/en-en/help/conditions.
Travelling with a bicycle brings extra difficulty as close to departure you're unlikely to find a train with bike spaces available. Your only option might be to refund and go the slow route by TER.
In 2022 I travelled from London to Bordeaux via Dover, Calais and Paris. Whilst most trains were flexible, the Paris-Bordeaux TGV required a bike reservation and I'd have been stuffed had I missed that train. In the end I booked two tickets (+ bike spaces) for different Paris-Bordeaux departures (one 6h after the other) and cancelled Plan B when I got to Montparnasse station on time. I had to pay the fee for cancelling but as an insurance policy it was well worth it.