how can I get user Time Zone in Wordpress if you don't know where the user comes from.
Let's say if a user is in USA I need to get USA Time Zone, if the user is in Germany I need to get Germany Time Zone.
Since WordPress is a server-side framework/CMS, it likely doesn't have the functionality you're looking for. If you're looking for ways to obtain this information, the most reliable would likely be to ask the user.
To make it as painless as possible for the user, this functionality could be achieved via client-side scripting (ie. JavaScript) where you attempt to infer the user's timezone:
-new Date().getTimezoneOffset()/60;
And then ask the user to confirm that it is the correct timezone. Keep in mind, client side code is run on the user's machine and can be disabled entirely.
ip_info("Visitor", "Country");