There is no way Python will know "2021-01-18 21:24:02" comes from which timezone because the information about the timezone is not in the string.
It could be 9:24 PM in USA, or Sydney, or Japan, or South Africa.
The most logical answer is the time came from UTC (or GMT), which is +0 because no timezone is provided.
The string itself must contain the information of timezone according to the format of various standards. See here for reference: https://www.utctime.net/z-time-now
Example:
ISO-8601 2021-01-29T04:49:28+0000
which show the timezone as UTC (+0000)
If the datetime is 2021-01-29T04:49:28+0800 , then the timezone is +8 or Singapore/Perth/China/Hong Kong time.
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