I would say a couple of the main things are:
- be consistent over a long time (most of the 200k people are doing it for years already, the once with 100+ subs are new)
- upload regularly (if you want to grow quicker upload more videos)
- be valuable, funny or controversial (depends on what you are going for)
- Do It. And this is a big one. I recently started creating YouTube videos myself, so I am by no means big (I currently have 77 subscribers). But since I started making the videos I changed so much. Got so much more comfortable in front of the camera. And people start to notice. So you yourself grow just buy doing it more regularly. This way you find your voice and become more a captivating speaker.
- work with other YouTubers if you can. Some kind of 'collaborative' content.
- share your show / videos on more platforms.
- make high quality videos and learn more about the craft of making good videos (editing as well as presentation skills).
Those are a couple starting points I would go for. It's not easy and it is a long process I would say. It takes time to build a following and I would assume that a Channel with 200k followers is just longer in the marked, more consistent and through that higher quality overall.