One of the first things I do when setting up a WordPress site, after I have settled on the theme is:
Create a Child Theme!
This preserves-protects customizations made through and after Theme updates.
I like using this WordPress plugin. When using the WordPress builtin Customizer is not enough – Create a child theme from your installed themes and customize styles, templates, functions and more with this plugin.
OEM Link:
https://wordpress.org/plugins/child-theme-configurator/