Time Zone Setup/configuration. Information about how country & location fetching the Timezone

Organization Name (Required - If you are an Oracle Partner, please provide the organization you are logging the idea on behalf of):

Schneider Electric

Description (Required):

Need more details about time zone setup/configuration.

-How is the UTC time zone being calculated as we don't find it in Manage Time Zones Setup page?
-How to take care of the time zone config for missing locations/states/cities etc.?
-Are there any validations enabled for Time zone field?

Use Case and Business Need (Required):

Business want to update the time zone details for locations wherever the data is missing for some countries