Flexbox

flex-shrink: 1 (default)

CSS
.container {
  display: flex;
}

.flex-item {
  flex-shrink: 1;
}
Box-1
Box-2
Box-3
Box-4
Box-5
Box-6
Box-7
Box-8
Box-9

flex-shrink: 0

Maintain the content size or mention width size

CSS
.container {
  display: flex;
}

.flex-item {
  flex-shrink: 0;
}
Box-1
Box-2
Box-3
Box-4
Box-5
Box-6
Box-7
Box-8
Box-9
CSS
.container {
  display: flex;
}

.flex-item {
  flex-shrink: 0;
  width: 100px;
}
Box-1
Box-2
Box-3
Box-4
Box-5
CSS
.container {
  display: flex;
}

.flex-item {
  width: 100px;
}

// Reduce size of 3 times compare to all
.box-4{
  flex-shrink: 3;
}
Box-1
Box-2
Box-3
Box-4
Box-5