This is an example sketch which pulls a timezone database from the internet. It then sets up a web page with the list of locales. When the user chooses one, the device tz is set, and the localtime is presented.
I have added geolocation to this sketch. It will try to use ipstack.com to geolocate your IP address. You must sign up at ipstack.com for a free (non-commerical) api key to use the autoZone functionality.