wp_admin_viewport_meta()

function wp_admin_viewport_meta() {
	/**
	 * Filters the viewport meta in the admin.
	 *
	 * @since 5.5.0
	 *
	 * @param string $viewport_meta The viewport meta.
	 */
	$viewport_meta = apply_filters( 'admin_viewport_meta', 'width=device-width,initial-scale=1.0' );

	if ( empty( $viewport_meta ) ) {
		return;
	}

	echo '<meta name="viewport" content="' . esc_attr( $viewport_meta ) . '">';
}