FlyerTalk Evangelist
Join Date: Nov 2018
Location: Istanbul, Turkey
Programs: TK Elite Plus,BAEC GGL,ITA Executive, AFKL Gold,QR Gold,HH Diamond,Bonvoy Gold,ALL Gold
Posts: 14,186
1- You are forced to check-in your carry-on at check-in to your final destination on all flights to/from Turkey regardless of the airline. You could still bring one personal item that could fit under the seat. If you're sitting in a bulkhead or emergency exit-row seat, the crew would allow you to put your personal item in the overhead lockers. However, they usually don't weigh the personal items.
2- You have a 3 x 23 kg checked baggage allowance + 1 x 8 kg checked baggage allowance ( for your carry-on ). Normally, your personal item that needs to fit under your seat could not exceed 4kgs but as I mentioned above, they usually don't weigh it.
The link that you've provided is the general cabin baggage rules before pre-COVID and it would not apply.