express-8.x-1.x-dev/themes/contrib/bootstrap/starterkits/less/THEMENAME.libraries.yml

global-styling:
  css:
    theme:
      css/style.css: {}

bootstrap-scripts:
  js:
    bootstrap/js/affix.js: {}
    bootstrap/js/alert.js: {}
    bootstrap/js/button.js: {}
    bootstrap/js/carousel.js: {}
    bootstrap/js/collapse.js: {}
    bootstrap/js/dropdown.js: {}
    bootstrap/js/modal.js: {}
    bootstrap/js/tooltip.js: {}
    bootstrap/js/popover.js: {}
    bootstrap/js/scrollspy.js: {}
    bootstrap/js/tab.js: {}
    bootstrap/js/transition.js: {}