This is pretty much doable with standard Bootstrap 4 classes. There is even a whole section in the documentation about the Card columns feature.
From the docs:
Cards can be organized into Masonry-like columns with just CSS by wrapping them in .card-columns. Cards are built with CSS column properties instead of flexbox for easier alignment. Cards are ordered from top to bottom and left to right.
Heads up! Your mileage with card columns may vary. To prevent cards breaking across columns, we must set them to display: inline-block as column-break-inside: avoid isn’t a bulletproof solution yet.
So, all you have to do is to wrap your .cards into a .card-columns container like this:
<div class="container">
<div class="card-columns">
<div class="card">
<img class="card-img-top" src="http://via.placeholder.com/1600x900/483D8B/ffffff?text=Card+1" alt="Card image cap">
<div class="card-body">
<h5 class="card-title">Card title that wraps to a new line</h5>
<p class="card-text">This is a longer card with supporting text below as a natural lead-in to additional content. This content is a little bit longer.</p>
</div>
</div>
<div class="card p-3">
<blockquote class="blockquote mb-0 card-body">
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.</p>
<footer class="blockquote-footer">
<small class="text-muted">
Someone famous in <cite title="Source Title">Source Title</cite>
</small>
</footer>
</blockquote>
</div>
<div class="card">
<img class="card-img-top" src="http://via.placeholder.com/1600x450/9400D3/ffffff?text=Card+2" alt="Card image cap">
<div class="card-body">
<h5 class="card-title">Card title</h5>
<p class="card-text">This card has supporting text below as a natural lead-in to additional content.</p>
<p class="card-text"><small class="text-muted">Last updated 3 mins ago</small></p>
</div>
</div>
<div class="card bg-primary text-white text-center p-3">
<blockquote class="blockquote mb-0">
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat.</p>
<footer class="blockquote-footer">
<small>
Someone famous in <cite title="Source Title">Source Title</cite>
</small>
</footer>
</blockquote>
</div>
<div class="card text-center">
<div class="card-body">
<h5 class="card-title">Card title</h5>
<p class="card-text">This card has supporting text below as a natural lead-in to additional content.</p>
<p class="card-text"><small class="text-muted">Last updated 3 mins ago</small></p>
</div>
</div>
<div class="card">
<img class="card-img" src="http://via.placeholder.com/1600x1600/FF1493/ffffff?text=Card+3" alt="Card image">
</div>
<div class="card p-3 text-right">
<blockquote class="blockquote mb-0">
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.</p>
<footer class="blockquote-footer">
<small class="text-muted">
Someone famous in <cite title="Source Title">Source Title</cite>
</small>
</footer>
</blockquote>
</div>
<div class="card">
<div class="card-body">
<h5 class="card-title">Card title</h5>
<p class="card-text">This is a wider card with supporting text below as a natural lead-in to additional content. This card has even longer content than the first to show that equal height action.</p>
<p class="card-text"><small class="text-muted">Last updated 3 mins ago</small></p>
</div>
</div>
</div>
</div>
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" rel="stylesheet"/>