Базовый макет Bootstrap 4, вложенный контейнер внутри container-fluid

.container-fluid {
    background: grey;
}

.container {
    background:wheat;
}

<link href = "https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" rel = "stylesheet"/>

<div class = "container-fluid">

    <div class = "container p-5">
      
      <div class = "row">
                                
          <div class = "col-md-12 pb-5">
      
              <h1>My First Bootstrap Page</h1>      
              <p>This part is inside a .container-fluid class.</p> 
              <p>The .container-fluid class provides a full width container, spanning the entire width of the viewport.</p>

          </div>

      </div>
      
       <div class = "row">
                                
          <div class = "col-md-6 pb-5">
      
              <h1>My First Bootstrap Page</h1>      
              <p>This part is inside a .container-fluid class.</p> 
              <p>The .container-fluid class provides a full width container, spanning the entire width of the viewport.</p>

          </div>
          
          <div class = "col-md-6 pb-5">
      
              <h1>My First Bootstrap Page</h1>      
              <p>This part is inside a .container-fluid class.</p> 
              <p>The .container-fluid class provides a full width container, spanning the entire width of the viewport.</p>

          </div>

      </div>

    </div>

</div>