How to read the Content Type header and convert into utf-8 while Gmail IMAP has utf8 and Outlook has ISO-8859-7?

So I get emails using imap from gmail and outlook.

Gmail encodes like this =?UTF-8?B?UmU6IM69zq3OvyDOtc68zrHOuc67IG5ldyBlbWFpbA==?= and outlook encodes like this =?iso-8859-7?B?UmU6IOXr6+ft6er8IHN1YmplY3Q=?=

Unfortunately I did not find yet any solution that will help me make this into readable text. Instead I am messing with:

mb_convert_encoding($body, "UTF-8", "UTF-8"); 

and

mb_convert_encoding($body, "UTF-8", "iso-8859-7");

but I am struggling to find a solution to solve this matter.

This is how I open the IMAP of my account (which has a lot of gmail and outlook messages)

$hostname = '{imappro.zoho.com:993/imap/ssl}INBOX';
$username = 'email@email.com';
$password = 'password';


/* try to connect */
$inbox = imap_open($hostname,$username ,$password) or die('Cannot connect to Zoho: ' . imap_last_error());

/* grab emails */
$emails = imap_search($inbox,'UNSEEN');

Any help?