In some cases, you want to review the document before saving, emailing, signing, … . The previewer Lightning component shows your document and proposes the actions to take.
Enabling with Clickjack protection:
In some cases when you generate the document, Visualforce page previewer fails to load with a blank page or white screen. This is because of the Clickjack security settings of Salesforce. To solve this issue, watch below video.
Delivery Overwrite Options: Never save (BASE64) or Do not save on preview (VIEW_THEN_SAVE):
Enable Previewer toolbar: makes it easy to zoom and print from the previewer
