My siblings taught themselves (I took lessons.) They only took lessons after they could play by ear, to improve their playing skills. They are much better at piano than I am, I never graduated year 4. So starting with lessons doesn’t always work out for the best anyway.
Just get yourself an easy book. If you practice an hour a day, and that means every single day, it should take about a year to become good enough to play easy pieces.
Also, fingering is really important. Don’t get into lazy fingering habits in the beginning, or you’ll just have to relearn fingering later on.