Determine the city by IP address

Hello.
I often use your articles and have learned a lot from them. However, I can't find a clear solution for displaying the city in the header of the website. I've been searching for a while and keep coming across the same article "City Selection Block on a Drupal Site (+ Automatically by IP)" by Nikita Petrov. To be honest, it's not clear what and where to import the databases, etc. Please help me understand or write an alternative article with screenshots on this topic. Thank you in advance.