David Kimura PRO said over 2 years ago on Importmaps in Rails 7 :
If anything, you would use Importmaps for JS libraries and then CSSBundling for the CSS libraries. That's why I'd prefer esbuild and cssbundling over importmaps to get to a, what feels like a normal way, of managing assets.

rails new my_app \
--javascript esbuild \
--css bootstrap

In fact, I just keep the flags in my .railsrc file

➜  ~ cat .railsrc
--javascript esbuild
--css bootstrap