It depends on the country you study in, whether you do part time or full time, whether you work at the same time, whether you do a taught or research degree, the subject area, the complexity of the topic studied, and how committed you are to writing it up.

Here is some useful information

https://www.phdstudies.com/article/how-many-years-does-it-take-to-complete-a-phd/

3 years only

If it is full time, it takes 3 to 5 years and double that if it is part-time.

If we take it as general, the best case scenario is 3.5 to 4 years, the avg case is about 5 years, and the worse case scenario we can say its about 7+ years. Actually, most students that take 7+ years usually don’t finish at all.