If you want Unicode code points (replace 1252 with the code page in question),

my $code_points = decode('cp1252', $cp1252_bytes);
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If you want UTF-16le, the encoding Windows calls "Unicode", continue with

my $utf16le_bytes = encode('UTF-16le', $code_points);
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decode and encode are provided by Encode. It's from_to can combine decode+encode.