Сделайте изображение дополнительным элементом, и вам нужно только применить переполнение к его родителю:
.features-box {
padding: 100px 0;
background-color: rgba(56, 74, 100, .1);
}
.content {
padding: 30px;
background-color: #fff;
position: relative;
}
.content:after {
content: '';
position: absolute;
width: 100%;
bottom: 0;
height: 2px;
left: 0;
box-shadow: 0 2px 2px 0 rgba(0, 0, 0, .6);
z-index: 9;
}
.advantages-box .left {
overflow: hidden;
}
.advantages-box .left img {
height: 100%;
width: 100%;
object-fit: none;
transition: .3s;
}
.advantages-box:hover .left img {
transform: scale(1.1);
}
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
<section class="features-box">
<div class="container">
<div class="row justify-content-center">
<div class="col-xl-10 advantages-box">
<div class="row h-100">
<div class="col-6 h-100 p-0 position-relative left">
<img src="http://placekitten.com/1000/500">
</div>
<div class="col-6 h-100 p-0 position-relative right">
<div class="content d-flex flex-column align-items-start text-left h-100">
<h5>What is Lorem Ipsum one?</h5>
<p>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</p>
<h5>What is Lorem Ipsum two?</h5>
<p>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</p>
</div>
</div>
</div>
</div>
</div>
</div>
</section>
Если вы хотите сохранить фоновое изображение:
.features-box {
padding: 100px 0;
background-color: rgba(56, 74, 100, .1);
}
.content {
padding: 30px;
background-color: #fff;
position: relative;
}
.content:after {
content: '';
position: absolute;
width: 100%;
bottom: 0;
height: 2px;
left: 0;
box-shadow: 0 2px 2px 0 rgba(0, 0, 0, .6);
z-index: 9;
}
.advantages-box .left {
overflow: hidden;
}
.advantages-box .left div {
height:100%;
background-position:center;
background-repeat:no-repeat;
transition: .3s;
}
.advantages-box:hover .left div {
transform: scale(1.1);
}
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
<section class="features-box">
<div class="container">
<div class="row justify-content-center">
<div class="col-xl-10 advantages-box">
<div class="row h-100">
<div class="col-6 h-100 p-0 position-relative left">
<div style="background-image:url(http://placekitten.com/1000/500)"></div>
</div>
<div class="col-6 h-100 p-0 position-relative right">
<div class="content d-flex flex-column align-items-start text-left h-100">
<h5>What is Lorem Ipsum one?</h5>
<p>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</p>
<h5>What is Lorem Ipsum two?</h5>
<p>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</p>
</div>
</div>
</div>
</div>
</div>
</div>
</section>
Другая идея без изменения HTML-кода заключается в использовании псевдоэлемента и наследования для фона:
.features-box {
padding: 100px 0;
background-color: rgba(56, 74, 100, .1);
}
.content {
padding: 30px;
background-color: #fff;
position: relative;
}
.content:after {
content: '';
position: absolute;
width: 100%;
bottom: 0;
height: 2px;
left: 0;
box-shadow: 0 2px 2px 0 rgba(0, 0, 0, .6);
z-index: 9;
}
.advantages-box .left {
overflow: hidden;
position:relative;
z-index:0;
}
.advantages-box .left:before {
content:"";
position:absolute;
top:0;
left:0;
right:0;
bottom:0;
background:inherit;
transition: .3s;
}
.advantages-box:hover .left:before {
transform: scale(1.1);
}
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
<section class="features-box">
<div class="container">
<div class="row justify-content-center">
<div class="col-xl-10 advantages-box">
<div class="row h-100">
<div class="col-6 h-100 p-0 position-relative left" style="background-image: url(http://placekitten.com/1000/500); background-repeat: no-repeat; background-position: center center;">
</div>
<div class="col-6 h-100 p-0 position-relative right">
<div class="content d-flex flex-column align-items-start text-left h-100">
<h5>What is Lorem Ipsum one?</h5>
<p>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</p>
<h5>What is Lorem Ipsum two?</h5>
<p>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</p>
</div>
</div>
</div>
</div>
</div>
</div>
</section>