I would stick with the regex, but since you asked and I've been looking for a good reason to use the unpack function...

use strict;
use warnings;

use Data::Dumper;

my $size = 2;
my $string='aabbccddee';

my $template = "a$size" x (length($string)/$size);

if (length($string) % $size){
    $template .= "a" . (length($string) % $size);
}

print "Unpack Template: $template \n\n";

my @parts = unpack($template, $string);

print Dumper(\@parts);
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Output:

Unpack Template: a2a2a2a2a2 

$VAR1 = [
          'aa',
          'bb',
          'cc',
          'dd',
          'ee'
        ];
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----
Coyote