Working with timezones can be tricky and if you do migration of data from/to somewhere. You might have to correct timezones. This snippet shows how you can change dates based on timezone difference.
Source code viewer
$given = new DateTime("2018-08-30T10:00:00", new DateTimeZone("Europe/Tallinn"));
$given->setTimezone(new DateTimeZone("UTC"));
$output = $given->format("Y-m-d\\TH:i:s");
echo $given->format("Y-m-d\\TH:i:s"); // Output: 2018-08-30T07:00:00
Programming Language: PHP