If you are visiting Turkey for the first time, yes, you can use your phone for 120 days without any problem. 120 days starts counting after phone is first used in Turkey with a Turkish Sim Card. After 120 days, you must register your phone or use a different phone. Registering phone is 1500 TL (2019 price) and it is very expensive. After 120 days, It makes more sense to use a different phone or if you have a dual sim phone use other slot.
In addition to this, your phone should be unlocked. You must be able to use the sim card of any operator.