I'll add some notes from my short time in Istanbul, didn't exactly go to plan but the report may be of use if anyone is ever out there.
With travel options restricted I decided to go Istanbul for a weekend just to get away somewhere. Plan was to be a tourist first of all as I've never been and then catch up with a regular from Morocco who moved there. But she disappeared a few weeks before, not been on her whatsapp nor any other social media so not sure what happened to her but that messed up the plan slightly.
I did a search for some other options and it seems twitter is the main place. Outcall seems to be most commmon and for some 2 hours minimum, prices usually circa 1000tl(£120) for 2 hours but varies a lot, also they only do outcall to 4/5 star hotels, I stayed in a 4 star for £30 a night around Taksim, was half price as not many tourists here currently. Once you find a twitter profile look at the hashtags, who they follow and suggested profiles and you will find many more, message them in turkish. I also found a website called ForumZamparalar some more girls advertise on here and they have reviews plus there are some posts on twitter girls too.
As I said I didn't have much luck, first night I saw @milyonbade she wants 800tl(£93) for 1 hour or 1300tl(£153) for two hours, the most expensive I came across. Said she was 24 but more like 34, body is good as per the pictures and service too but if I had seen her face I wouldn't of booked, older than expected and has that puffy look with fake lips.
Next night arranged another girl she did minimum 2 hours for 1100tl (£128) she looked promising, some good comments on that forum but she cancelled a few hours before, I messaged a couple others but too late to arrange something else.
I heard Bars/clubs around Taskim square have freelancers in, probably more so before coronavirus, I didn't see any clubs open, I was in a few bars and the only one I saw some in was dubliner Irish pub which is just off the square but they didn't look that great, it was quiet in there too. The Moroccan girl I knew had sent me videos from around Taksim, usually smoking shisha in hotel bars with other Moroccan girls so definitely options in them too, Nova Plaza Crystal hotel and Taksim intercontinental were two, though again probably outside coronavirus times. I did read that as mentioned earlier in this thread lots of scams operate in some of these clubs to lure tourists in and hit them with huge bills, so be careful of that.
Also coming back from that irish bar to Taksim square the place were you re-enter the square had a handfull of girls stood around, obvious hookers.