I'd do it something like this:

#!/usr/bin/perl -w
use warnings;
use strict;

my $data = <<DATA;
16 character ID \x00\x01\x02\x03\x10\x11\x12\x13
DATA

my $id = unpack ("A16", substr $data, 0, 16, '');

print "$id\n";

while (length $data) {
    my (@bytes) = unpack ('c4', substr $data, 0, 4, '');
    
    printf "0x%02x ", $_ for @bytes;
    print "\n";
}
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Prints:

16 character ID
0x00 0x01 0x02 0x03 
0x10 0x11 0x12 0x13 
0x0a
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