Page editing in backend redirecting to 404 page not found with url /post.php

WordPress stores the domain in a lot of places – not just the options table – and in many places it’s serialized, so if the new domain does not have the same number of characters as the old domain, a lot of things can break if you try to manually search and replace.

You can either use a tool like WP-CLI, or look for a database migration plugin. The plugins tend to be the quickest, easiest way unless you’re already familiar with WP-CLI. Some hosts also provide migration services, so you might want to leave it to them if they provide the service for free.