Playing against higher-rated opponents does not necessarily lower your rating and in some cases can actually improve it. Here again, it depends upon the percentage of games you win, and how much higher the opponent’s rating is. If the opponent is rated too far above you and they win the match easily by winning a high percentage of games, that won’t hurt your rating, as it is the expected outcome. But your rating can get a boost if you end up playing a close match. On the other hand, such a match can lower your rating if you end up not winning a high enough percentage of games.