Add “File Size” Column the WordPress Media Library

add this code to your fucntions.php

it will add File Size column to the media library you can see file sizes without clicking to media one by one…

// Add a new 'File Size' column to the media library.
function add_file_size_column( $columns ) {
    $columns['file_size'] = __( 'File Size', 'textdomain' ); // Replace 'textdomain' with your theme's text domain, or just use 'File Size' if you don't have one.
    return $columns;
}
add_filter( 'manage_upload_columns', 'add_file_size_column' );

// Populate the 'File Size' column with the actual file size.
function populate_file_size_column( $column_name, $post_id ) {
    if ( 'file_size' == $column_name ) {
        $file_path = get_attached_file( $post_id ); // Get the file path.

        if ( file_exists( $file_path ) ) {
            // Retrieve the file size.
            $file_size = filesize( $file_path );

            // Format the file size.
            echo size_format( $file_size, 2 );
        } else {
            echo '—';
        }
    }
}
add_action( 'manage_media_custom_column', 'populate_file_size_column', 10, 2 );