If you have a working Curl incantation, I would always start out by converting it to Perl using my Curl to LWP converter.

Running your Curl command gives me the following HTTP::Tiny code:

#!perl
use strict;
use warnings;

use HTTP::Tiny;

my $ua  = HTTP::Tiny->new( 'verify_SSL' => '1' );
my $res = $ua->request(
    'GET' =>
'https://management.azure.com/subscriptions/[SUBSCRIPTION_ID]/provider
+s/Microsoft.Web/sites?api-version=2016-08-01',
    {
        headers => {
            'Content-Type'  => 'application/json',
            'Accept'        => '*/*',
            'User-Agent'    => 'curl/7.55.1',
            'Authorization' => 'Bearer [TOKEN]'
        },

    },
);



__END__

Created from curl command line
curl -X GET -H "Authorization: Bearer [TOKEN]" -H "Content-Type: appli
+cation/json" https://management.azure.com/subscriptions/[SUBSCRIPTION
+_ID]/providers/Microsoft.Web/sites?api-version=2016-08-01
[download]