Does the plugin automatically detects the country (IP based location) & switch currency accordingly?

Yes it do!

Since version 2.3, WooCommerce introduced a function that allows you to set the default customer location to their actual location by using his IP.  Price Based on Country uses the WooCommerce Geolocation function to display price and currency based on customer country.

Documentation related topic:

• Configuring WooCommerce Geolocation
• Geolocation with cache support
• How to test Price Based on Country