Can we pull specific item fields in Feed Aggregator?

Lets assume we have the following rss content:

  <?xml version="1.0" encoding="UTF-8"?>
  <rss version="2.0" xmlns:content="http://purl.org/rss/1.0/modules/content/">
    <channel>
      <atom:link xmlns:atom="http://www.w3.org/2005/Atom" href="http://source.com/rss/events"  rel="self" type="application/rss+xml"></atom:link>
      <title>Upcoming Events</title>
      <link>http://domain.com/calendar</link>
      <description>Upcoming Events</description>
      <item>
        <title>New Years Day Event</title>
        <link>https://domain.com/events/20170101</link>
        <guid>123456</guid>
        <date>01/01/2017</date>
        <start>08:00</start>
        <end>12:00</end>
        <description>Happy New Years!</description>
        <content>
            This is a cool new years party!
        </content>
      </item>  
    </channel>
  </rss>

Let's then say I created an aggregator block and wanted this information to display as follows:

New Years Day Event, 01/01/2017, 08:00-12:00

Is this possible? I have tried my best to find applicable aggregator documentation for Drupal 8, and what little I have found has been quite minimal. I've played around with configurations, and can't seem to find anywhere to select which fields to display on the aggregator block. I'd greatly appreciate if someone could provide an answer of point me to the proper documentation for Drupal 8 feed aggregator.