JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-3.4.1.slim.js"></script>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.css">
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.16.0/umd/popper.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.js"></script>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.css">
<!-- 
  Bootstrap docs: https://getbootstrap.com/docs
-->

<div class="container">
  <div class="row">
    <div class="col col-sm-5">Span 5</div>
    <div class="col col-sm-3">Span 3</div>
    <div class="col col-sm-2">
      <div class="col col-sm-12">Span 2</div>
      <div class="col col-sm-12">Span 2</div>
    </div>
  </div>

  <div id="replica" class="row">

  </div>
</div>

CSS

.row {
  background: #f8f9fa;
  margin-top: 20px;
}

.col {
  border: solid 1px #6c757d;
  padding: 0px;
}

JavaScript

var json = [         {
                        "Name": "span5",
                        "ColSpan": 5
                    },
                    {
                        "Name": "span3",
                        "ColSpan": 3
                    },
                    {
                        "Name": "span2",
                        "ColSpan": 2,
                        "children":[
                          {
                              "Name": "span2",
                              "ColSpan": 12
                          },
                          {
                              "Name": "span2",
                              "ColSpan": 12
                          }
                        ]
                    }
    ];
                
var replica = document.getElementById('replica');
var str  = "";
for(var i = 0; i < json.length; i++) {
	str += '<div class="col col-sm-' + json[i].ColSpan + '">' + (json[i].children ? 
  json[i].children.reduce((acc,child) =>(acc + '<div class="col col-sm-' + child.ColSpan +'">' + child.Name + '</div>'),"" ) 
  : json[i].Name) + '</div>';
}
replica.innerHTML = str;