string $size_names )
Filters the names and labels of the default image sizes.
(string) Array of image size labels keyed by their name. Default values include 'Thumbnail', 'Medium', 'Large', and 'Full Size'.
image_size_names_choose‘ filter allows modification of the list of image sizes that are available to administrators in the WordPress Media Library.
This is most commonly used to make custom image sizes available from selection in the WordPress admin.