How do you deal with Nerves in Chess?

In chess (and in other games, I compete in like pocket billiards and golf) my mental game (nerves) seems to be holding me back a great deal. My knowledge, ability, and skill seem to be at a level where I can perform much better than I do and I psych myself out often. There have been times when playing pool where I kind of fell into a sort of flow state where I had no nerves and everything seemed effortless performed way better than I normally do and beat people way out of my leauge (even to the point of being accused of being a hustler on more than one occasion) but then nerves take over and I go back to mediocre play.

For example, I will never forget one time playing golf on a very hard course on the Front 9 I looked like a scratch golfer and had to chip-ins, and on the back 9, I looked like a beginner or one night in a pool tournament where in the first two games I played I upset high-level players then lost to someone rated much lower than me in the next game. I have had similar experiences playing chess too.

I know everyone experiences this from time to time but it seems to be happening to me way too much and the performance shift seems to be way too dramatic. It seems to be the last piece of the puzzle for me to grow in ability much faster and I believe my ELO would jump up dramatically in a short time.

How do you all deal with nerves when playing have you ever entered a "flow state/in the game mindset" how drastically do your results change? Any tips?

Thanks

Nerves are normal. A certain anxiety is even good to prevent stupid mistakes. As you play more you will get less nervous.