Flat Head on Newborn.

Basically I just wanted to know if it’s normal for most babies to have a flat head due to laying on their back for the majority of the newborn stage. I know there’s different shapes and levels to it but I was just wondering if it eventually goes away on its own and how do you prevent it? I have a 2 month old and I been wanting to lay him on his sides when he naps since he sleeps flat on his back every night. I also bought him one of those newborn pillows with a hole on center to give his little head some cushion. Any recommendations.