$ perl -le'binmode STDOUT, ":utf8"; print "\x{00E4}";'|od -c
0000000 303 244 \n
0000003
####
$ perl -CO -le'use charnames ":full"; print "\N{LATIN SMALL LETTER A WITH DIAERESIS}";'|od -c
0000000 303 244 \n
0000003
####
$ perl |od -c
use Encode;
my $c = decode "latin1", "\xe4";
$c = uc $c;
$c = chr (1 + ord $c); ## further mangling
print encode "latin1", $c;
__END__
0000000 305
0000001
$ perl |od -c
use Encode;
my $c = decode "latin1", "\xe4";
$c = uc $c;
$c = chr (1 + ord $c);
print encode "utf8", $c; ## <-- change here
__END__
0000000 303 205
0000002
####
use utf8;
my $á = 42;
print $á, "\n";
__END__
42