How do I lower my rating without being BM?

Ratings adjust rapidly when you are new.

Yes. It will adjust your elo and it will reflect wherever you should be. May happen quickly.... Don't worry You won't lose to a 1200 on purpose if your true rating is 300
Don't worry, just play. You do not need to lose on purpose. Play your best game and if your real rating is 300 you will most likely lose to the stronger opponents you are facing and learn in the process. If you do not lose all the time but manage to win about as much as you lose, then you are not really 300 but much closer to that 1200.
And if it is blitz, the rating should adjust in just a couple of days, since the games are very short and you can play multiple games a day.

Just keep playing but make sure it makes you happy. This site is testing you out if you can defeat a higher rated player it will add hundreds of points if you defeated him but lose only 1-3 points if you lose on a higher rated.

The guy is already 300 rated so good job. There are only 2 problems:
1. rating manipulation is cheating
2. the rating of 300 is a rating of someone who learned the rules of chess yesterday. Being 300 after months of playing is ridiculous.

The guy is already 300 rated so good job. There are only 2 problems:
1. rating manipulation is cheating
2. the rating of 300 is a rating of someone who learned the rules of chess yesterday. Being 300 after months of playing is ridiculous.
There are those who dont care about getting better and just play
take care not to disparage them if you feel like being a good person.
The guy is already 300 rated so good job. There are only 2 problems:
1. rating manipulation is cheating
2. the rating of 300 is a rating of someone who learned the rules of chess yesterday. Being 300 after months of playing is ridiculous.
It's actually possible, especially for someone who learns the game at an advanced age. I was attending a local club a few years ago (pre-COVID) when one elderly player wished to play the game, After several months, the player improved, but still hung pieces around - and at some point allowed stalemate to occur, right in front of me (I was a spectator for a game between the player and another novice player at the time).