class.wp-scripts-partial.php

<?php 
    // near line 347
		// build the attributes for the <script> tag
		// including the type and src attrs.
    
    $tag_attributes = [];
    /** defaults always set **/ 
    $tag_attributes['type'] = "text/javascript";
    $tag_attributes['src'] = $src;
    
		$tag_attributes_extra = $this->get_data( $handle, 'tag_attributes');
    
		if( $tag_attributes_extra )
      // combine 'must have' attrs with custom ones
      $tag_attributes = wp_parse_args($tag_attributes_extra, $tag_attributes); 
			// chance for plugins, etc to filter attributes if needed.
			apply_filters('script_tag_attributes', $tag_attributes, $handle );
			// add any additional attributes if set in the registration of script
			foreach( $tag_attributes as $attr => $attr_val ){
				$attrs .= esc_attr($attr)."='".esc_attr($attr_val)."'&nbsp;";
			}
		$tag = "{$cond_before}{$before_handle}<script {$attrs}></script>\n{$after_handle}{$cond_after}";

functions.wp-scripts.php

<?php
// around line 96
function wp_enqueue_script( $handle, $src = false, $deps = array(), $ver = false, $tag_attrs = false, $in_footer =
false ) {
	global $wp_scripts;
	if ( !is_a($wp_scripts, 'WP_Scripts') )
		$wp_scripts = new WP_Scripts();

	if ( $src ) {
		$_handle = explode('?', $handle);
		$wp_scripts->add( $_handle[0], $src, $deps, $ver );
		// set the tag_attributes as 'extra' data
		$wp_scripts->add_data($_handle[0], 'tag_attributes', $tag_attrs);
		if ( $in_footer )
			$wp_scripts->add_data( $_handle[0], 'group', 1 );
	}
	$wp_scripts->enqueue( $handle );
}

theme-functions.php

<?php
function wpdocs_theme_name_scripts() {
  $tag_attrs = array(
    'async' => 'true',
    'data-cfasyc' => 'false'
    );
    wp_enqueue_script( 'script-name', get_template_directory_uri() . '/js/example.js', array(), '1.0.0', $tag_attrs, true  );
}
add_action( 'wp_enqueue_scripts', 'wpdocs_theme_name_scripts' );