Maintain 3 sites with same content

I’m about to begin a site redesign. We have 3 sites, which I’m going to call https://www.mypage.com, https://www.mypage.in and https://www.mypage.sg.

Is there a way to maintain all the content in 1 location for ease of maintenance, but lets say a user enters a site from https://www.mypage.sg, and navigates the site, the url maintains the url he/she enters from e.g. https://www.mypage.sg/page1, https://www.mypage.sg/page2.
The same principal should apply if the user enters from *.com or *.in.

Most of the content will be the same, except for 1 or 2 pages, but I want to keep the url of the same locale for the visitor\customer.
What would be the best set up in wordpress.