You'll need to walk the structure

For which there is the fine Data::Rmap module:

use strict;
use warnings;
use JSON;
use XML::Simple;
use Data::Rmap qw(rmap_ref);
use Data::Dumper;

my $text = '{"a":"x","b":true}';
my $result = decode_json($text);
print Dumper($result);
rmap_ref { $_ = "$_" if JSON::is_bool($_) } $result; # or numify, like
+ ikegami shows above
print Dumper($result);
my $rec = XMLout( $result, RootName => 'root', SuppressEmpty => 1);
print Dumper($rec);
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Output:

$VAR1 = {
          'a' => 'x',
          'b' => bless( do{\(my $o = 1)}, 'JSON::XS::Boolean' )
        };
$VAR1 = {
          'a' => 'x',
          'b' => 'true'
        };
$VAR1 = '<root a="x" b="true" />
';
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