dynamically-define-acf-fieds.php

function register_custom_fields() {

    
    $fieldArray = [];

        array_push($fieldArray,
            array(
                'key' => 'sample_field_onee',
                'label' => 'Sample Field',
                'type' => 'text',
                'prefix' => '',
                'instructions' => '',
                'required' => 0,
                'conditional_logic' => 0,
                'wrapper' => array(
                    'width' => '',
                    'class' => '',
                    'id' => '',
                ),
                'default_value' => '',
                'placeholder' => '',
                'prepend' => '',
                'append' => '',
                'maxlength' => '',
                'readonly' => 0,
                'disabled' => 0,
            ),  
        );

    if( function_exists('acf_add_local_field_group') ) :

        acf_add_local_field_group(array (
            'key' => 'lang_fields',
            'title' => 'Language Fields',
            'fields' => $fieldArray,
            'location' => array (
                array(
                    array(
                        'param' => 'post_type',
                        'operator' => '==',
                        'value' => 'page',

                    ),
                ),
            ),
            'menu_order' => 0,
            'position' => 'normal',
            'style' => 'default',
            'label_placement' => 'top',
            'instruction_placement' => 'label',
            'hide_on_screen' => '',
        ));

    endif;
};
add_action('acf/init', 'register_custom_fields');