I think the voting age could be raised a little, like 20 years for the national elections, but the municipal elections could have the limit lowered by a year or two.
This way we could see if the argument that lowering the voting age increases voting interest holds any water, and let younger people have power in smaller circles and vote when they are still under the guidance of their guardians. This could provide a soft landing into the political world.
Setting the age higher for the big elections can make it be seen as more valuable, since it's a resource available to fewer people. People might vote and think more about voting if they value it more.
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