How can I make world clocks (time zone clocks)?

Hello fellow devs!

I am thinking of making world clocks like the pic below:

I searched here and Youtube, but in every case they use os object which use local time in their computers.
So I am afraid the times displayed on clocks are different according to the players’ location.

And so I am wondering how can I make world clocks like those on above pic.
Does anyone have good idea?


using https service u can get all the world times using this site

An exmaple:

and all the avaible timezones


Thank you so much for very useful info.
It seems to work fine.