The Clock widget does not keep the correct time.
I loaded the clock widget and set it for New York City (NYC) to show the East coast time zone. I looked at it a little after 6 pm and the time it displayed was 2:26. I checked and it was set for New York City and when I clicked on it to open the widget it showed the correct time. When I closed it the widget display still showed the incorrect time. I removed the widget and reinstalled it, again set New York City (NYC). It displayed correctly - at first. After 5 minutes I looked at it and the widget time was about 2½ minutes behind the actual time.
Bottom line is, the Clock widget does not keep correct time.
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iPhone 7, iOS 14