Use of sales_quote_address_collect_totals_after events Magento 2.

Magento 2 you can use sales quote address collect totals after the event to Collect address total related data after Magento completed the process for a  current quote total.

Event Name to used:
sales_quote_address_collect_totals_after

Using the above event in the observer, you can fetch specific quote data, shipping_assignment, and total related data for a cart.

Simple code snippet for use events, Define events.xml

<?xml version="1.0"?>

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="sales_quote_address_collect_totals_after">
        <observer name="your_event_observeranme" instance="Jesadiya\Totals\Observer\MyObserver" />
    </event>
</config>

Create an Observer file to fetch quote related data,

<?php

namespace Jesadiya\Totals\Observer;

use Magento\Quote\Model\Quote;
use Magento\Framework\Event\Observer;
use Magento\Framework\Event\ObserverInterface;
use Magento\Quote\Api\Data\ShippingAssignmentInterface;

/**
 * Class MyObserver
 */
class MyObserver implements ObserverInterface
{

    /**
     * @param Observer $observer
     * @return void
     */
    public function execute(Observer $observer)
    {
        /** Fetch Address related data */
        $shippingAssignment = $observer->getEvent()->getShippingAssignment();
        $address = $shippingAssignment->getShipping()->getAddress();

        // fetch quote data
        /** @var Quote $quote */
        $quote = $observer->getEvent()->getQuote();

        // fetch totals data
        $total = $observer->getEvent()->getTotal();
    }
}

You can use the above way your observer with the required data after collecting totals in Magento 2.

Check Use of sales_quote_address_collect_totals_before events Magento 2.

You can refer for more details to use in your custom module using the Magento_Quote module.
You can be interested to learn  A Complete List of events used in Magento 2.