Link structure change in internal links

if you are asking about making a change to permalinks – try this guide: https://yoast.com/help/how-do-i-change-the-permalink-structure/

if you asking about searching the database to replace URLs – try Better Search Replace plugin

you might consider redirecting URLs to avoid broken links for visitors – try a redirection plugin

You should go to wordpress admin panel > settings > permalinks to change your links structure.

and if you are looking to replace all internal links from content.

your text and images content links are in database

use plugins “Better Search Replace – WordPress plugin“

https://www.ads-software.com/plugins/better-search-replace/

it will help you to replace your internal links.