Notice the if ( is_page()
line. It’s to indicate that the snippet only works with pages, not posts. Pull it out of the if condition if you want to apply it site-wide.
function wpdocs_replace_content( $text_content ) {
$text = array(
'chamber' => '<strong>chamber</strong>',
);
$text_content = str_ireplace( array_keys( $text ), $text, $text_content );
return $text_content;
}
add_filter( 'the_content', 'wpdocs_replace_content' );