If the tickets were never used at all, they can be sold or gifted to anyone.
They can be used, as-is, for ANY child who would be at WDW aged 3yrs to under 10 years old.
If the tickets were never used at all, you or anyone else can upgrade them to current adult tickets
using their value to help pay for the upgrade cost.
The value for a 5-day Park Hopper MagicYourWay ticket from prior to the year 2016 is $414.29 with tax.