It protects you only if you have chosen the right VPN provider.
Of course if you choose some random VPN that was advertised in a youtube video that may as well be a downgrade depending on what your ISP does with your data already.
But if you choose a honest VPN provider, who's values aligns with yours, and does not share (neither collect) any data on your usage and traffic, then that can easily be better.

Also keep in mind that ISP's often operate knowing that they are the only provider in the area. Or the only usable one, or that the others aren't better either. There's no competition, and they make use of the fact that they can do whatever they want that is legal (a lot of things is), because the user can't just switch to another that does not do it.
However, there's a competition between VPNs. Unfortunately most of that competition is driven by lies, but fortunately not all of it is.