Display tabs

add_filter('breadcrumb_settings_tabs', 'breadcrumb_settings_tabs_20200203');

function breadcrumb_settings_tabs_20200203($settings_tabs){

    $current_tab = isset($_POST['tab']) ? $_POST['tab'] : 'options';


    $settings_tabs[] = array(
        'id' => 'custom_atb',
        'title' => sprintf(__('%s Custom','breadcrumb'),'<i class="fas fa-star-of-life"></i>'),
        'priority' => 99,
        'active' => ($current_tab == 'custom_atb') ? true : false,
    );

    return $settings_tabs;

}

Display tab content

add_action('breadcrumb_settings_tabs_content_custom_tab','breadcrumb_settings_tabs_content_custom_tab');

function breadcrumb_settings_tabs_content_custom_tab(){

    $settings_tabs_field = new settings_tabs_field();

    $custom_option = get_option('custom_option');

    ?>
    <div class="section">
        <div class="section-title"><?php echo __('Custom tab settings','breadcrumb'); ?></div>
        <p class="description section-description"><?php echo __('This is custom tab descriptions.','breadcrumb'); ?></p>

        <?php

        $args = array(
            'id'		=> 'custom_option',
            //'parent' => 'breadcrumb_options',
            'title'		=> __('Breadcrumb custom option','breadcrumb'),
            'details'	=> __('Custom option descriptions','breadcrumb'),
            'type'		=> 'text',
            'value'		=> $custom_option,
            'default'		=> '',
        );

        $settings_tabs_field->generate_field($args);


        ?>

    </div>
    <?php


}

View post on imgur.com

Save options

add_action('breadcrumb_settings_save', 'breadcrumb_settings_save_20200203');

if(!function_exists('breadcrumb_settings_save_20200203')) {
    function breadcrumb_settings_save(){


        $custom_option = sanitize_text_field($_POST['custom_option']);
        update_option('custom_option', $custom_option);

    }
}