It really depends what you are intending to use this for. There are many sides to machine learning, but you don't have to know all of them. To name a few very different concepts:

MLOps (Corsera has an excellent series on this) Reinforcement learning GANs Graph neural networks

I would say that once you have an idea about what most of these topics involve it is time to actively dive into some of them by actually trying to code up solutions in them, or downloading well known github projects and trying to run them yourself.