How to create content type "News" A site user needs to be able to add news to Drupal 8 site. 

Some news might be own contents and some news might be from external sources. 

If the site user is adding a news which is from an external source, the site user should be able to add a node by just entering the source URL(i.e. examplesite.com/xyz).

If the site user is adding a news which is their own content, the site user should be able to add a node by entering the contents which may have number of paragraphs with titles and few images for each node. 

Site user also should be able to add nodes without any coding. 

I already create a role and the user for the role. 

I created a content type "News" which currently have title and body fields. 

How can I create a content type which meets the above requirements?
It sounds like you're off to a good start. Next, you'll need to add a new field to your content type for links to external news articles.

Home &gt;&gt; Administration &gt;&gt; Structure &gt;&gt; Content types &gt;&gt; News &gt;&gt; Manage fields

/admin/structure/types/manage/news/fields/add-field

Add a new field of type Link and label it something like News Link. Save the field.

Decide if you want to allow only one link to be saved in this field, or multiple values. Save the field settings.

Decide if you want to allow external links only in the field (the default is "Both internal and external links"). Save settings.

After that, you'll still need to make a whole bunch of decisions about how to display News content items ... but the Link field seems to be a missing link in your description.

Good luck!