By Default, In Magento2  Billing address is displayed with the Payment method, and the second option to display billing address is on the Payment page.

If you have a custom requirement like, Display the Billing address before all the payment methods you need to do customization for that.

Create a di.xml file at the location,
app/code/Magemonkeys/BillingAddressBeforePayment/etc/frontend/di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <!-- Set Billing address above the payment method plugin -->
    <type name="MagentoCheckoutBlockCheckoutLayoutProcessor">
        <plugin name="move_billing_address_above_payment_method"
                type="MagemonkeysBillingAddressBeforePaymentPluginBlockCheckoutLayoutProcessor"/>
    </type>
</config>

Based on the XML file, Create a Plugin Class, app/code/Magemonkeys/BillingAddressBeforePayment/Plugin/Block/Checkout/LayoutProcessor.php

<?php declare(strict_types=1);

namespace MagemonkeysBillingAddressBeforePaymentPluginBlockCheckout;

use MagentoCheckoutBlockCheckoutLayoutProcessor as CheckoutLayoutProcessor;

/**
 * Move Billing address to top
 */
class LayoutProcessor
{
    /**
     * @param CheckoutLayoutProcessor $subject
     * @param array $jsLayout
     * @return array
     */
    public function afterProcess(
        CheckoutLayoutProcessor $subject,
        array $jsLayout
    ): array {
        $paymentLayout = $jsLayout['components']['checkout']['children']['steps']
        ['children']['billing-step']['children']['payment']['children'];

        if (isset($paymentLayout['afterMethods']['children']['billing-address-form'])) {
            $jsLayout['components']['checkout']['children']['steps']
            ['children']['billing-step']['children']['payment']['children']
            ['beforeMethods']['children']['billing-address-form']
                = $paymentLayout['afterMethods']['children']['billing-address-form'];

            unset($jsLayout['components']['checkout']['children']['steps']
            ['children']['billing-step']['children']['payment']
            ['children']['afterMethods']['children']['billing-address-form']);
        }

        return $jsLayout;
    }
}

before method is used to display content before the payment methods.