This is what I did to use bootstrap in a component I was testing out.

npm install bootstrap
npm install jquery
npm install popper.js

 

In CSS file
@import '../../node_modules/bootstrap/dist/css/bootstrap.min.css';

In js file
import 'bootstrap';

After that I was able to use all of the bootstrap stuff.  It included everything in the component when I pushed it to the instance, which of course makes the component bigger.  Its not clear thou if you use bootstrap in say 10 components and they all load on the page if the system is going to have 10 instances of bootstrap loaded into memory or just one.