Here is one solution:

use strict;
use warnings;

use charnames ':full';

open(my $fh, ">:raw", "test.plp"); 
binmode($fh, ":encoding(ucs2le)"); 
print $fh "\r\n"; 
close $fh;

#test
open(PLP,"<:encoding(ucs2le)","test.plp");
my $string;
sysread(PLP, $string, 100);
printf("0x%02x ", ord($_)) for (split //, $string);
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This prints:

0x0d 0x00 0x0a 0x00
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Your original problem is due to the fact that there is a :crlf layer, and the sequence between layers.