use strict;
use warnings;

use Encode qw( encode );

my $enc = 'iso-latin-1';  # Desired encoding
my $text = chr(130);   # Any char supported by iso-latin-1 and $enc

utf8::downgrade(my $text_off = $text);
utf8::upgrade  (my $text_on  = $text);

# Encode text on output
my $from_off = encode($enc, $text);
my $from_on  = encode($enc, $text);
print("bytes are ", ($from_off eq $from_on ? 'same' : 'diff'), "\n");