To address the issue, consider applying a fixed height and width along with some Margin to your cards.
Alternatively, you can modify the bootstrap class from col to col-4, which will provide three columns of the exact same size.
<div class="container ">
<div class="row pt-5">
<div class="col-4">
<div class="card">
<div class="card-body">
<h5 class="card-title">
Heading</h5>
<p class="card-text">SomeText</p>
<a href="#" class="btn btn-primary">View</a>
</div>
</div>
</div>
<div class="col-4">
<div class="card">
<div class="card-body">
<h5 class="card-title">
Heading</h5>
<p class="card-text">SomeText</p>
<a href="#" class="btn btn-primary">View</a>
</div>
</div>
</div>
<div class="col-4">
<div class="card">
<div class="card-body">
<h5 class="card-title">
Heading</h5>
<p class="card-text">SomeText</p>
<a href="#" class="btn btn-primary">View</a>
</div>
</div>
</div>
</div>
<div class="row pt-5">
<div class="col-4 offset-4">
<div class="card">
<div class="card-body">
<h5 class="card-title">
Heading</h5>
<p class="card-text">Lorem Ipsum is simply dummy text of the printing and typesetting industry.
Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an
unknown printer took a galley of type and scrambled it to make a type specimen book. It has
survived not only five centuries, but also the leap into electronic typesetting, remaining
essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets
containing Lorem Ipsum passages, and more recently with desktop publishing software like
Aldus PageMaker including versions of Lorem Ipsum.
</p>
<a href="#" class="btn btn-primary">View</a>
</div>
</div>
</div>
</div>
</div>