From reading the documentation it would appear that indeed LWP will return you a proper Perl string with properly decoded text if the correct Content-type header is present in the code. If the pages you are downloading are not in UTF-8 and they do not contain a Content-type header specifying what encoding they are in, then

$response->decoded_content(default_charset => 'utf-8')
[download]

will not work and you will need to use some method to guess the correct encoding. But if those pages do have proper headers and/or you can otherwise assume they are in UTF-8, then yes that should work.

There is a one-line "any-encoding - to - utf-8" conversion in Perl, but it requires you to know what encoding you're starting with. The function to use is the decode function in Encode.