looks_like_cp1252 is useless in this context. The following string is unambiguously cp1252, yet looks_like_cp1252 reports otherwise.

#!/usr/bin/perl

use strict;
use warnings;
use feature qw( say );

use Search::Tools::UTF8 qw( looks_like_cp1252 );

my $text = "\xC9ric";
say looks_like_cp1252($text) ?1:0;   # 0
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Therefore, you appear to be recommending the use of

my $txt;
if (is_valid_utf8($text)) {
   $txt = decode('UTF-8', $bytes);
} else {
   $txt = decode('Windows-1252', $bytes);
}
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But that requires parsing UTF-8 strings twice for nothing. That is why I didn't mention this possibility when I posted a solution that only parses UTF-8 strings once.

my $bytes = '...';
my $txt;
if (!eval {
   $txt = decode('UTF-8', $bytes, Encode::FB_CROAK|Encode::LEAVE_SRC);
   1  # No exception
}) {
   $txt = decode('Windows-1252', $bytes);
}
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