Time Zone Conversion

I have this Spreadsheet that has different country, Is it possible that it will auto convert the time into PHT Time (GMT +8) which is in Column A.

For example:
Its 3PM (Cell G1) in Bhutan. I want it to be converted in GMT +8
So therefore the time for GMT+8 will be 5PM and will be shown in Cell A1.

Also there will be an automated identifier in Column B that will identify if that time is for morning shift or night shift.
The morning shift is 12PM til 8PM
While the night shift is 8PM til 11AM.

Please help me thanks!