Can I give the col-md-1.5 in bootstrap?

You cloud also simply override the width of the Column…

<div class="col-md-1" style="width: 12.499999995%"></div>

Since col-md-1 is of width 8.33333333%; simply multiply 8.33333333 * 1.5 and set it as your width.

in bootstrap 4, you will have to override flex and max-width property too:

<div class="col-md-1" style="width: 12.499999995%;
    flex: 0 0 12.499%;max-width: 12.499%;"></div>