How do I break past a plateau and reach new people with my content?

Growing slowly is still growing, and a plateau is not a wall so much as a sign that what got you here has done its job. The people it was going to reach, it reached. Getting to new ones usually means changing something, not just doing more of the same thing harder. Plateaus break at the edges, not the center. Look at what is already working and ask who is just outside it: a nearby topic you have not touched, a format you avoid, a place your kind of people gather that you are not in yet. New reach almost always comes from a new door, not from knocking louder on the one you have already opened. So run one experiment. Pick a single new format, topic, or platform, commit to it for a month without judging it by day three, and watch who shows up. Most experiments will not move much. One will, and that one teaches you where your next audience actually lives. You only need a few of those to get unstuck.