From the patch notes:
*Players can unlock Kingdom Power Levels by:
Collecting Kingdom Troops
Ascending and leveling kingdom troops
Unlocking Traits on kingdom troops
It mentions ascending as one of the things you can do to increase kingdom levels but that’s not true, only number of troops, their level and their traits increase the kingdom’s level.
Unless they mean ascending gives a troop more room to further level it up… but that’s a bit misleading in my opinion, since ascending has no direct influence