Embed and display PDF viewer
You can use the Embedded Google Docs Viewer module for that 


  Drupal 8
  
  This module provides a formatter for the File field type. This
  formatter presents the file as a fully rendered object within a web
  page - i.e. it displays the contents of the file as appropriate to its
  filetype (Adobe Acrobat .pdf, Microsoft Word .doc/.docx, Microsoft
  Excel .xls/.xlsx, Microsoft Powerpoint .ppt/.pptx), using the Google
  Docs embedded rendering engine.


There are some other modules but those are in Dev version. Have a look at the Comparison of PDF viewer modules