GMRS radio question

More power does increase the range, but at the frequencies you're talking about the range will be limited by hills, trees, buildings, or any other physical obstruction. They say in real estate, it's Location, Location, Location... in radio, it's Elevation, Elevation, Elevation. If you can get on top of a hill, building or tower that puts you higher than other obstructions, you'll increase your range significantly, especially if the receiving station is also on a hilltop.