JSFiddle - React, Tailwind, and code Playground

HTML

<a id="IncNum" href="">Chamada Completa</a>
<form action="" method="post">
<div>
    <input type="text" name="fixo[]" value="FIXO 1"><br>
<a class="Extra" href="">Extra</a>
</div>
</form>

JavaScript

//Chamada completa
$(document).ready(function() {
    var campoInsere1 		= $("form");
	var botao1				= $("#IncNum");

    var counter1			= 1;
    $(botao1).click(function(e){
        e.preventDefault();
            counter1++;
			
            $(campoInsere1).append('<div><input type="text" name="fixo[]" value="FIXO '+counter1+'"><br><a href="" class="remove_field">Remover</a>&nbsp;&nbsp;&nbsp;<a class="Extra" href="">Extra</a></div>');
    });
    
    $(campoInsere1).on("click",".remove_field", function(e){
        e.preventDefault(); $(this).parent('div').remove(); counter1--;
    })


 
//1 formulário extra, dentro de grupo
    var campoInsere2        = $("form div");
    var botao2      		= $(".Extra");

    var counter2			= 1;
    $(botao2).click(function(e){
        e.preventDefault();
            counter2++;
            $(campoInsere2).append('<label><input type="text" name="variavel[0][]" value="Extra"><a href="" class="remove_field">Remover</a></label>');
    });
    
    $(campoInsere2).on("click",".remove_field", function(e){
        e.preventDefault(); $(this).parent('label').remove(); counter2--;
    })
});