Flexbox

For Rows

flex-wrap: nowrap (default)

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

flex-wrap: wrap

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

flex-wrap: wrap-reverse

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

For Columns

flex-wrap: nowrap (default)

CSS
.container {
  display: flex;
  flex-direction: column;
  height: 400px;
  flex-wrap: nowrap
}
Box-1
Box-2
Box-3
Box-4
Box-5
Box-6
Box-7
Box-8
Box-9

flex-wrap: wrap

CSS
.container {
  display: flex;
  flex-direction: column;
  height: 400px;
  flex-wrap: wrap
}
Box-1
Box-2
Box-3
Box-4
Box-5
Box-6
Box-7
Box-8
Box-9

flex-wrap: wrap-reverse

CSS
.container {
  display: flex;
  flex-direction: column;
  height: 400px;
  flex-wrap: wrap-reverse
}
Box-1
Box-2
Box-3
Box-4
Box-5
Box-6
Box-7
Box-8
Box-9

Suppose if enough height then it is not problem