Are we able to change the bar width?

You can change the bar width using CSS:

<style>
.wider-bar .calendar_default_event_bar,
.wider-bar .calendar_default_event_bar_inner {
  width: 12px;
}
</style>

And add the "wider-bar" CSS class to the event:

dp.onBeforeEventRender = args => {
  if (args.e.type == "pending") {
    // ...
    args.data.cssClass = "wider-bar";
  }
}