Dear @Ajay S

Use the flex-wrap class to wrap flex items. Try to replace your code with:

<div class="row mx-3 mb-0 text-center">
  <div class="col mt-1 mb-2">
    <div class="btn-group flex-wrap mt-1">
      <label mdbBtn color="panel" class="btn-md waves-effect waves-light m-1" [(ngModel)]="checkModel1.first" mdbCheckbox mdbWavesEffect>
        Clicks 1000 <mdb-icon fas icon="arrow-up" class="white-text"></mdb-icon> 25%
      </label>
      <label mdbBtn color="panel" class="btn-md waves-effect waves-light m-1" [(ngModel)]="checkModel1.second" mdbCheckbox mdbWavesEffect>
        Impressions 1000 <mdb-icon fas icon="arrow-up" class="white-text"></mdb-icon> 25%
      </label>

      <label mdbBtn color="panel" class="btn-md waves-effect waves-light m-1" [(ngModel)]="checkModel1.third" mdbCheckbox mdbWavesEffect>
               CTR 5% <mdb-icon fas icon="arrow-up" class="white-text"></mdb-icon> 25%
      </label>

      <label mdbBtn color="panel" class="btn-md waves-effect waves-light m-1" [(ngModel)]="checkModel1.fourth" mdbCheckbox mdbWavesEffect>
                                Position 4.14 <mdb-icon fas icon="arrow-up" class="white-text"></mdb-icon> 25%
      </label>
  </div>
  </div>
 </div>

Hope it helps.

Best Regards, Bartosz.