Changing Astra Theme to Flatsome One Without Destroying The Website

Create a staging site, activate the new theme and make the necessary changes. When happy, copy the changes back to the live site:

https://www.wpbeginner.com/wp-tutorials/how-to-create-staging-environment-for-a-wordpress-site/

Hello, thank you for your answer. What about changing the theme on the local computer throught laragon you know I would download the whole website using wp migration and then start customizing with the new theme. when it is done, I upload it back to the live web site.