Using a VPN makes it a bit harder for your ISP and the French espionage apparatus to siphon your data as much as anyone not using one (ISPs have to keep a history for up to a year as well, it is a legal requirement to make it easier to spy on people). Of course with the laws in Five Eyes countries it won’t actually protect your privacy 100% if you get your VPN service from there but I don’t think France has the budget or capabilities to keep track of every foreign VPN company even with cooperation from other spy agencies.