The higher the resolution, more sharper it will be, test which resolution best suits your project!
Viewing post in Pixel Engine for RPG Maker MZ comments
Since the plugin auto scales according to the resolution, the higher the resolution, the better it will look not only for you but for those who play like this, your project is at 1920x1080, which would be the maximum, if a person who has a 1280x720 monitor is going to see it in good quality despite rescaling