Main domain and its subdomains?

Question

Search Engine Optimization

Good night everyone, I have such a question that is not clear to me and I can’t comprehend it ......
There is a site https://site.ua/, the site is written by YII2, the SEO specialist tells me that I need to make subdomains for a site like sample list of subdomains below. It turns out that I have to copy the project for each subdomain ... this type is necessary for promotion in cities.

https://berdichev.site.ua/
https://kiev.site.ua/
https://odessa.site.ua/

Explain to me what to do right, when a user selects a city, https://kiev.site.ua/ is immediately substituted for him, and of course, being in Kiev, all this is displayed on the site.
I apologize if the thought was bad!

Answer 1

You do not need to copy, all domains will be processed by one script, in the script you must determine from which domain, and show the corresponding content