For your information, there are two ways to change your style (CSS) for your template.
First of all, you can change your style from build/asseta/css/style.css then upload the changed file to your live server.
The second way, If you want to change your style through SCSS. In that case, you need to follow the below steps to prepare your local environment and run it on your local. You can also minify the CSS and JS. After your changes, you need to upload your changes assets (CSS or JS) to your live server.
Steps to make live:
On this page