Sorry to say but as far as we are viewing your Site, the Turkish Characters seems to be appearing fine: https://ibb.co/kyKKjdc
Can you please be more specific in your issue, exactly what characters are not appearing correctly? Please share some Images of the issue too for our better understanding.
For example, characters such as Ğ,ş,ğ in the Hakkımızda page, in the menu area and cookie area below give an error. You can see the examples in the attachment.
Sorry to hear about the inconvenience, can you please share valid WP-ADMIN Login details of your Site in the below listed format on which you are facing the issue so that we can proceed further and check the issue on your Site and assist you accordingly.