WordPress ➧ Change Locale Dynamically in WordPress

functions.php

/**
 * Change Locale Dynamically in WordPress.
 *
 * @author Guy Dumais.
 * @link https://en.guydumais.digital/change-locale-dynamically-in-wordpress/
 */

// Filters all language attributes in the html tag.
add_filter( 'language_attributes', $af = function( $output, $doctype ) {

    if ( strpos($output, 'en-US') !== false ) {
        $output = str_replace('en-US', 'en-CA', $output);
    }
    return $output;

}, 10, 2 );
unset( $af );

// Filters all language attributes in social tags (og:).
add_filter( 'locale', $af = function( $locale ) {

    if( 'en_US' == $locale ) {
        $locale = 'en_CA';
    }
    return $locale;

}, 10 );
unset( $af );