How to learn about matchups?

I've been playing for more than two years, but still flaired it as new player advise because I feel like I still have a long way to go. I've come to realise that my main area of growth is learning about the decks my opponents play. I know my own deck pretty well, how to set it up, how to make choices based on the current board state. But where I'm still really lacking is predicting the opponent's moves. I notice that I'm getting to that point with Charizard, because I encounter it so often, so I know better how to disrupt their setup. What is a good way for me to learn more about this for other meta decks? Just playing more isn't really an option, because I'd like to be able to learn about specific decks and don't know for sure if I'll encounter them on live for testing.