Displaying relative dates in a Views Exposed Filter
Edited - You can apply datepicker to the field, as Jquery Ui date picker is available in Drupal8. For reference see to this

Or,

you can programmatically alter the view query in hook_views_query_alter()

function module_name_views_query_alter(ViewExecutable $view, QueryPluginBase $query) {
 // Query alter to provide dynamic date ranges.
 if ($view-&gt;id() == 'VIEW ID' &amp;&amp; $view-&gt;current_display == 'page_1')
 {
    foreach ($query-&gt;where[0]['conditions'] as $key) {
      if (array_key_exists(':node__field_start_date_time.field_start_date_time_value[]', $key['value'])) {
        // do anything you want...
        ...
        ...
      }
    }
 }