It's not necessarily the higher Hz that will make you better, but it's the fact you will have optimal settings in order to get better, in my experience.
For example in CSGO, trying to play a game with 30fps, more input lag, slower reactions to enemies appearing etc will only allow you to get to a certain level. Once you move to 100+fps and 144hz, your ceiling to improve becomes higher since the game is smoother and you can react as fast as your personal ability allows.
It won't make you much, if at all, better instantly, but you may be able to get better over time.
For example in CSGO, trying to play a game with 30fps, more input lag, slower reactions to enemies appearing etc will only allow you to get to a certain level. Once you move to 100+fps and 144hz, your ceiling to improve becomes higher since the game is smoother and you can react as fast as your personal ability allows.
It won't make you much, if at all, better instantly, but you may be able to get better over time.