Thanks for your contact.
First of all, please check the theme changelog: https://www.portotheme.com/wordpress/porto/documentation/changelog/
The 6.2.3 version of the theme was released on (1.19.2022) around 2 years ago.
And you are updating the theme from a 2-year-old theme version to the very latest version.
If you carefully check the changelog, there are a lot of features and styling that have been added and removed into/from the theme.
So the best possible way is to, clone your site as a test site and then try to update the theme and plugins onto your test site first so that if any issue occurs you can solve it on the test site and once all is fine, you can then migrate your site from a test site to live site.
How to update the theme, please read our theme documentation here: https://www.portotheme.com/wordpress/porto/documentation/update-theme/
How to update the plugin, please read our theme documentation here: https://www.portotheme.com/wordpress/porto/documentation/update-plugins/