WordPress at a glance
function is not described

_wp_add_additional_image_sizes() WP 5.3.0

Add additional default image sub-sizes.

These sizes are meant to enhance the way WordPress displays images on the front-end on larger, high-density devices. They make it possible to generate more suitable srcset and sizes attributes when the users upload large images.

The sizes can be changed or removed by themes and plugins but that is not recommended. The size "names" reflect the image dimensions, so changing the sizes would be quite misleading.

This is an internal function for using it by WP core itself. It's not recommended to use this function in your code.

No Hooks.

Return

````. Null. Nothing.

Usage

_wp_add_additional_image_sizes();

Changelog

Since 5.3.0 Introduced.

Code of _wp_add_additional_image_sizes() WP 5.7

<?php
function _wp_add_additional_image_sizes() {
	// 2x medium_large size.
	add_image_size( '1536x1536', 1536, 1536 );
	// 2x large size.
	add_image_size( '2048x2048', 2048, 2048 );
}