If you want to have calendar for from date and to date and also to date calendar days always will be greater than from date field, then below scenario will help.
<?php $form = ActiveForm::begin(['id' => 'profile-form']); ?>
.....
<?= $form->field($model, 'from_date')->widget(DatePicker::classname(), ['dateFormat' => 'php:M d, Y', 'options' => ['readonly' => true], 'clientOptions' => [ 'changeMonth' => true, 'changeYear' => true, 'yearRange' => '1980:'.date('Y'), 'onSelect' => new yii\web\JsExpression('function(selected) { var dt = new Date(selected); dt.setDate(dt.getDate() + 1); $("#filter-date-to").datepicker("option", "minDate", dt); }')]]) ?>
<?= $form->field($model, 'to_date')->widget(DatePicker::classname(), ['dateFormat' => 'php:M d, Y', 'options' => ['readonly' => true, 'id' => 'filter-date-to'], 'clientOptions' => [ 'changeMonth' => true, 'changeYear' => true, 'yearRange' => '1980:'.date('Y')]]) ?>
.....
<?php ActiveForm::end(); ?>