Well I actually just linked a couple of videos earlier in another thread. You have the ever classic ranked anxiety, A youtuber by the name of Foxdrop, he's very easy to find, did a couple of videos on dealing with ranked anxiety. One was brief and gave some quick tips and had a minor explanation of it, the other was a much longer and more in depth video that goes into a good bit of detail, gives explanations, and overall is quite a good video.
Foxdrop
That is a link directly to his youtube channel, the videos are about two months old, so you'll have to scroll down a bit. I know that watching other players in higher elo through streaming or youtube helped me, you'll also find that a number of them also do educational content and you can learn quite a bit just by watching them.
What helped me was literally just the fact that they were not only so calm about it, but also were so comfortable, that they could talk about what was going on, and explain why things were happening. So there was really no reason for me to be so nervous about simply playing the game. I'm also a very big fan of classical piano music, which is extremely relaxing, and frankly helps calm my anxiety in all things.
The most important thing that I got out of Foxdrop's videos is that you should treat ranked like any other game, pretend that you're just queuing up for normal games, and most importantly try and have fun, after all that's really the point of playing a game isn't it?