You cannot change how fast characters age. They are hardcoded to age half a year pr turn.
You can however change how fast the date passes, to make it match.
Go to *\Medieval II Total War\mods\Stainless_Steel_6\data\world\maps\campaign\imperial_campaign and open the descr_strat.txt file.
Locate this part, and change Timescale to 0.50
Code:
start_date 1100 summer
end_date 1620 winter
timescale 1.50
Be aware that this will also mean that you'll have huge cities and citadels much sooner than normal.
There's also some Submods out there, that changes this, but also changes buildingtime, and polulation growth, to make it match better.