functions.php

/**
 * Hides checkout fields based on the products in the cart
 *
 * @param  array $fields
 * @return array
 */
function conditional_checkout_fields_products( $fields ) {
    $cart    = WC()->cart->get_cart();
    $has_tag = true;

    foreach ( $cart as $item_key => $values ) {
        $product = $values['data'];

        if ( ! has_term( 'your-tag', 'product_tag', $product->id ) ) {
            $has_term = false;
            break;
        }
    }
    
    if ( $has_term ) {
      unset( $fields['billing']['billing_company'] );
    }

    return $fields;
}
add_filter( 'woocommerce_checkout_fields', 'conditional_checkout_fields_products' );