Search other website content in Main Sharepoint page

I work on SharePoint Server 2016 On-premises version. Is it possible to search other website content from the main SharePoint site. The other website can be both SharePoint and non-SharePoint websites.

For example:

  1. There is a website called and it has several documents, etc.
  2. Now, from my SharePoint page using search, can I get that website content inside my SharePoint page?
  3. If yes, please give a me walk around about the workflow and methods to approach the same.