It doesn't resize the screen. It changes the amount of the game that is drawn. If you increase the resolution using any of the current plugins for it, you're increasing the number of tiles drawn on the screen. Put simply: if you made a map that is supposed to be exactly one screen in size for 1280x720, and the user changes it to 1920x1080, then the map will appear smaller than it should be.
RMMV does scale to the display resolution while maintaining aspect ratio and the view resolution that is set by plugins. Barring a plugin that changes the actual display resolution (which, again, I would use if it were available), the most you should be allowing the user to change is the aspect ratio, which you would set to predetermined view resolutions (e.g. 1280x720 for 16:9, 1280x960 for 4:3, etc.)
If all you're asking is if it's possible, it is. All settings are essentially plain text, so they can be modified by any program.