The websites which are exist in Plesk but is not resolved to it from the Internet it happens when a website was created for tests, recently migrated or its DNS zone has not propagated properly, this are the common errors of this issue.
Solution: To accessing a website using Plesk Preview feature.
Below are the following steps for accessing a website using Plesk Preview feature.
Login into Plesk Panel >> Go to Websites & Domains >> example.com >> select the option preview

After click on the preview option it will open the website into the new tab of the browser