How to Filter WordPress Post Preview in Google Analytics?

First of all go to your Analytics dashboard, now select the property in which you want to create the filter and click on Admin (with gear icon).

After that click on Filter in the views (Create View) section and set up the filter by following the steps below.

After that type Filter Name and select Custom in Filter type.

Here in the Exclude section, select the Request URL in the Filter field.

Write "preview=true" in the Filter Pattern and save the setting.