You may have purchased a MacBook with a different keyboard layout. Because of personal reasons, I choose to use an English keyboard but sometimes need to use special Turkish letters such as ş or ğ.
Changing the keyboard layout from the top right menu is not efficient and interrupts my work and motivation. After some search, I see that I can change some files and add needed features into my customized English layout.
I can write Turkish letters by just long pressing.
You can see that g (long press) + 1 will write ğ
If you want to use these file just visit https://github.com/guncebektas/macbook-keyboard-for-Turkish-accents