A good, reliable VPN provider will make you very hard to track and it would require a lot of effort.
However, 100% anonymity is very difficult to achieve and requires a lot of effort on your side.
There is so much more to being anonymous than just using a VPN – for example, you would have to avoid registering to any services, do zero online shopping, and generally avoid anything that could put you online.
Sounds tough, right? Well, it’s nearly impossible.