Knowing the benefits of having a VPN on your smartphone in the US can be vital for your privacy. Our article goes over the types of data that can be collected through your phone, how parties in the US can access that data, and how a VPN protects you.
No, VPNs are helpful if you want to appear as if you are browsing from another country or if you need to hide your traffic from your isp or wifi provider. It does not provide you additional security through encryption or anything like that, your traffic is already encrypted through https. Tom Scott has a great video on it.
https://youtu.be/WVDQEoe6ZWY