You don’t need to use a VPN, WoW isn’t region locked by IP. Your sole advantage would be potential lower latency.
Using a VPN isn’t forbidden nor leads to a ban, it merely masks your source public IP and changes your network routes.
I’d just make a new account - intercontinental latency is way too miserable, but if you can live with it, you can keep playing the US version.
LA/BR servers are sadly in Chicago.