Navigate to a URL with the standard__webPage Page Reference Type

The navigation service uses a PageReference object to describe pages. A new PageReference type of standard__webPage wraps a raw URL so that you can navigate to external websites

Where: This change applies to orgs with Lightning components in Lightning Experience, Lightning communities, and all versions of the Salesforce app.

The standard__webPage type replaces the force:navigateToURL event. See pageReference Types in the Spring ’19 Lightning Components Developer Guide.