Urban sprawl as distinct from urban horizontal expansion is most cases than none is haphazard. I have not visited Istanbul, but from my experiences and researches conducted in the country and of studies of Istanbul, I have come to know it is nuisance in several respects which I have point out latter. In a picture of either Ankara or Istanbul in a study some people are behind a house waiting police van to pass away and then start squatter houses. As such, most of sprawl is made up congested squatter and illegal colonies in defiance of city plan. Obviously, sprawl resulted high density congested colonies become slums and their livability in terms of crowding, unhygienic condition, less refreshing of fresh air due to narrow winding lanes and congestion and lack of green and open places is worst. Obviously these are highly polluted from indoor and outdoor pollution, drainage is also likely to be poor causing stagnation of water. Further it is hard for police to petrol a sprawling city which is sprawling in different directions. This results in increased crime rates and delinquency and compromising security of citizens.The sprawl also create problems of transport and traffic. If all or a few traits of a sprawling city obtain, it may readily concluded whether urban sprawl increase the livability of İstanbul or not.

One of the main problems of Istanbul metropolitan area is expansion and being a megapolis. In the past, there was a problem of illegal housing (shanty houses/ towns or slums) but today these houses or neighborhoods are not trendy. In Turkey, there is a trend of renovation or reconstruction of old and unplanned quarters of the cities to the highly populated modern housing zones. I think one of the main problems is lack of green spaces in Istanbul and other large cities of Turkey.

I have written a newspaper article on importance of trees and green spaces in large cities of Turkey.

https://www.researchgate.net/publication/230718806_Toplum_ehirlerdeki_aalara_da_sahip_kmal!?ev=prf_pub

Article Toplum şehirlerdeki ağaçlara da sahip çıkmalı!

Urban sprawl will not enhance livability in Istanbul but rather it will cause serious environmental consequences to the study. The outward expansion of the city will give rise to leap frog and haphazard development which will result in the destruction of many green spaces which have been found to greatly enhance the livability of cities. The limited green spaces such as parks, gardens, trees, forests, wetlands will make it difficult for many social and recreational activities to take place. Furthermore, health and environmental benefits that the city can gain from the green spaces to improves its livability will be lacking.

https://www.researchgate.net/publication/230738894_Peri-Urban_to_Urban_Landscape_Patterns_Elucidation_through_Spatial_Metrics

https://www.researchgate.net/publication/229826816_Empirical_patterns_of_the_influence_of_Spatial_Resolution_of_Remote_Sensing_Data_on_Landscape_Metrics