Multiple domain to a control panel/hosting

Hello Everyone, I found a website, where they have one laravel app. which is their main control panel/dashboard . Let's say , they have their main domain as :

" XYZ dot com " consists a users table in its database.

users table -> id, username, email

now, they have two more domains, say those are "abc dot com " and "pqr dot com". but they are under the parent laravel app . they does not have any separate laravel app .

when someone visits "abc / pqr dot com" the URL does not change to the parent domain ( Xyz dot com) but they can view the users from the parent domain.

If any record gets changed to the parent app , obviously both the child gets the updated values. Now , I want to know, how they do it , or by which technique its possible.

I found a post here in laracasts regarding this behaviour. the link is

https://laracasts.com/discuss/channels/laravel/laravel-multidomain-application

but i don't understand the whole process. as i am new in this field, can anyone please tell me a bit more in a very specific bit by bit way like " which file to change / which technique should i use ? " . And what kind of hosting should i use ?

My apologies for asking such a nice question a very harder way and Thanks for the answer.