David Kimura PRO said 10 months ago on Importmaps in Rails 7 :
  I would probably use their provided gem for bootstrap. But for other things where a gem isn't provided, I am not quite sure of the best method yet. I think that this will be one of the growing pains as we'd have to find out the best routes for these things. I can see other libraries like FullCalendar where this too would be a concern.

# Gemfile
gem 'bootstrap', '~> 5.1.0'

# app/assets/stylesheets/application.scss
@import "bootstrap";

# app/javascript/application.js
//= require "bootstrap"