Lasers obey the inverse square law as perfect collimation isn't possible. But I guess as a practical matter it does make it easier to achieve a particular energy level at a target. You still apparently need megawatt scale lasers just to discern a signal from Alpha Centauri, though: https://academic.oup.com/mnras/article/516/2/2938/6668809 (I dunno how to calculate the other way around--from here to there--as it's partly a function of the origin star's luminosity.)