Using localhost to develop client's website

There are several tutorials online about moving the developed Wordpress site form XAMPP to the client server.
You can use a WP plugin. E.g:

Or you can do it manually. E.g:

Regardless of what method you use, I would recommend that you have a dedicated dev machine, or a dev virtual machine on it, and edit the machine’s host file (its virtual host section) to point the client’s domain to the nachine’s XAMPP server. (Then all requests for the client’s WP site from your dev machine will go to your local WP site.)

That could also save you from search and replace all absolute URLs in the exported database.

Edit the “host” file: