The published date of the reviews, local and API, are only placed in the schema markup. However, they can also be included in the display output such as after the rating or before the message as an example.
To have the date display, we first need to add it to an area of the review template. There are numerous developer hooks available but as an example, let's output the date at the end of the author template. This area includes the name, image, tagline/website, and rating.
Adjusting the Date format
The default format returned is Y-m-d (2018-01-31). If you would like to adjust this like the example above, you would use the below filter.
The returned string should be formatted according to the PHP date/time spec.