[Are there any default or plugin effects that make the edges less pixelated?]

 

Doing it manually would take time and I always miss something, I would like to know if there is any effect that helps to make the edges less pixelated. In this image I use 3 layers, sea, land, political. It looks like it's small, but I've increased the image size and the pixels turn into large clusters of pixels into a square.

[Good plugins with tools to better make maps (political, etc...)]

I like to make political maps based on what happens in games (mostly grand strategy games like Crusader Kings, Europa Universalis, Victoria), and I know there are good tools for that already on paint.net, but some things take time and you need one good proficiency, I would like to know if there are plugins that make the life of those who make maps easier or that add new tools for different styles, below are a map that I have already made using paint.net. Unfortunately I can't show some more because of the maximum 256kbps I can send.