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:

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

Create an Observer file to fetch quote related data,

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.