JSFiddle - React, Tailwind, and code Playground

HTML

<input type="button" id="btn1" onclick="buttonClicked()" value="Button 1" />
<input type="button" id="btn2" onClick="check2()" value="Button 2" />
<input type="hidden" id="btn_CheckValue" value="0" />

<p id="p1" class="hide">Hello you</p>
<p id="p2" class="hide">First click the other button</p>

CSS

.hide{
  display: none;
}

.show{
  display: block;
}

JavaScript

function buttonClicked(){
    document.getElementById("btn_CheckValue").value = "1";
}

function check2() {
    let btnValue = document.getElementById("btn_CheckValue").value
    let p1 = document.getElementById("p1")
    let p2 = document.getElementById("p2")
    
    if (btnValue == "1"){
    	p1.classList.toggle("show");
      p2.classList.add("hide");
    }
    else{
    	p2.classList.toggle("show");
      p1.classList.add("hide");
    }
    
}