I searched for hours, and I tried almost everything suggested.
This worked for almost every entity :
$input = "ažškunrukiš ? àéò ??? ©€ ?? ? ?? ? R?";
echo htmlentities($input, ENT_HTML5 , 'UTF-8');
result :
āžšķūņrūķīš ○ àéò ∀∂∋ ©€ ♣♦ ↠ ↔↛ ↙ ℜ℞rx;