Check for any Spa in good hotels (3 or 4 star) .. Even walk-ins are allowed.. try your luck at few .. don’t speak about it at reception. Speak directly to the girl. Istanbul or European women run them with Thai massage therapists. Probably due to easy visa policy may be you will find young stunning Thai massage therapists in Turkey compared to 40 + age therapists in UK … the difference is real… They even do “Hammam” after massage where you are given a bath with no clothes on . (A hammam is a traditional public steam bath rooted in Middle Eastern, North African, and Ottoman cultures, combining wet heat, full-body exfoliation, and communal cleansing.)
If you are not given a good looking therapist in first attempt, try the second time. Make the owner lady a friend and ask her anyone good ? Do not hesitate. She will get the message .. in the end it’s business for all of them … for the owner .. for the therapists.. these parlours are run independently and doesn’t belong to the hotel. Probably they pay rent.
I don’t know the scene at local Thai massage centres.. you may not get lucky there due to stricter rules. If I remember correctly police do not care about prostitution in hotels .. but elsewhere it is taken seriously. I had been to Istanbul thrice before 2022.