Add Custom Settings Tab for Number Field to WooCommerce https://wpsites.net/?p=114654

Custom WC Settings Tab

add_action('woocommerce_settings_tabs_exchange_rates', 'add_exchange_rate_usd_field');
add_action('woocommerce_admin_field_number', 'add_exchange_rate_usd_field');
// Add custom exchange rate field to WooCommerce settings under a new tab
function add_exchange_rate_usd_field() {

    woocommerce_admin_fields(array(
        array(
            'type' => 'title',
            'id' => 'exchange_rates_tab_title',
            'title' => __('Exchange Rates', 'woocommerce'),
        ),
        array(
            'title' => __('Exchange Rate (USD)', 'woocommerce'),
            'type' => 'number',
            'id' => 'exchange_rate_usd',
            'default' => '',
            'desc_tip' => true,
        ),
        array(
            'type' => 'sectionend',
            'id' => 'exchange_rates_tab_end',
        ),
    ));
}

add_action('woocommerce_update_options', 'save_exchange_rate_usd_field'); // Correct hook for saving options
function save_exchange_rate_usd_field() {

    if (isset($_POST['exchange_rate_usd'])) {
    
        update_option('exchange_rate_usd', sanitize_text_field($_POST['exchange_rate_usd']));
        
    }
    
}

add_filter('woocommerce_settings_tabs_array', function($settings_tabs) {

    $settings_tabs['exchange_rates'] = __('Exchange Rates', 'woocommerce');
    
    return $settings_tabs;
    
}, 50);