I could not find anything on CPAN...

That's because it's overkill for a module. As ikegami said:

use Date::Manip;
use List::Util qw(reduce);

sub earliest {
    reduce { Date_Cmp( $a , $b ) < 0 ? $a : $b } map { ParseDate($_) }
+ @_
}

sub latest {
    reduce { Date_Cmp( $a , $b ) > 0 ? $a : $b } map { ParseDate($_) }
+ @_
}

my $e = earliest( @dates );
my $l =   latest( @dates );
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