The official code reference for
$size (string|array) (Optional) Registered image size to retrieve the source for or a flat array of height and width dimensions.
I'm using the following parameters:
$img_url = get_the_post_thumbnail_url(get_the_ID(), array('300' , '170'));
But it doesn't return the size I want.
The registered image sizes are 150 x 150, 300 x 300 and 1024 x 1024.