DateTime automatically uses DST, but only if your date is in a timezone that observes daylight savings.

use 5.010;
use DateTime;
use DateTime::Format::Strptime;

# Choose a datetime in the southern summer.
my $later = DateTime->now(time_zone => 'UTC')->add(months => 6);

# Choose an output format that includes time zone.
$later->set_formatter(DateTime::Format::Strptime->new(pattern => '%F %
+T %z'));

# An abstract time zone; no daylight savings.
say "UTC+10: ",
    $later->clone->set_time_zone('+1000');

# Queensland, Australia does not observe daylight savings.
say "Brisbane: ",
    $later->clone->set_time_zone('Australia/Brisbane');

# But New South Wales does!
say "Sydney: ",
    $later->clone->set_time_zone('Australia/Sydney');
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