lucia.intelisano

If post doesn’t have a set featured image, 
WP Autoset Featured Image Plus check if text contains an image. If yes, set this as featured image, 
if not, you can set any external url image. Otherwise, leave field empty. 
Easy and fast!
Features include:

WP Autoset Featured Image Plus

Check for an image inside text editor or use external images from anywhere as the featured image of your pages and posts.

xaraartech

Abuzer

Adds functionality to search images from post page and attach as featured image. 
You will require to create an API key on bing for search API. 
GOTO: https://azure.microsoft.com/en-us/services/cognitive-services/bing-image-search-api/ or https://dev.cognitive.microsoft.com/docs/services/56b43f0ccf5ff8098cef3808/operations/571fab09dbe2d933e891028f 
And generate your “Ocp-Apim-Subscription-Key”

External featured image from bing

Adds functionality to search images from post page and attach as featured image.

WP Autoset Featured Image Plus vs External featured image from bing