Will a flat spot on a child's head, older than 2 years old, continue to minimize over time as their head grows? we were told our sons head would round

The practice of: putting babies to sleep on their backs has contributed to more "flat heads." Some have treated this with a helmut, usually at 4-12 months of age, though it is not clear this is more effective than trying to avoid lying on back during the day.As the child and his skull grows, the flattening will improve. It may not be perfectly symmetrical, but is not a cosmetic/social/brain development problem