how to change the size of images wordpress code example
Example: create custom image size wordpress
add_image_size( 'custom-size', 220, 180 ); // 220 pixels wide by 180 pixels tall, soft proportional crop mode
add_image_size( 'custom-size', 220, 180, true ); // 220 pixels wide by 180 pixels tall, hard crop mode
add_image_size( 'custom-size', 220, 220, array( 'left', 'top' ) ); // Hard crop left top