You get the byte length of characters when you use the bytes pragma. How about this (untested):

print "char#\tlength1\tlength2\n";
for (32..500) {
    print;
    print "\t";
    print length chr;
    print "\t";
    {
        use bytes;
        print length chr;
        no bytes;
    };
    print "\n";
};
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