If you are looking for a simple template or set up to automate your changes in your HTML or SaSS components feel free to clone this project. It uses GULP4 and BrowserSync to handle the automation.
If you would like to fully understand how this works, check out my medium post Setting up Gulp 4 for Bootstrap, SASS, and BrowserSync to learn more about the source code and how to modify the Boostrap package and your SaSS file.
After you clone this project you may try to install all dependencies using
$ npm install
Before you start the server, you need to install gulp 4 globally.
$ npm install gulp -g
Then run the command below.
$ gulp watch
If you want to try running testing the browser without installing gulp globally. Try running the command below.
$ node_modules/gulp/bin/gulp.js watch
Browsersync should automatically open a browser on port 3000.