//No package manager is provided but you can use a third party one such as chromebrew
//First though, your chromebook has to be in developer mode: https://www.androidpolice.com/how-to-enter-chrome-os-developer-mode/
//In crosh (Ctrl+alt+T) run this:
shell
curl -Ls git.io/vddgY | bash
//To install an app, run crew install app_name
//For example:
crew install filezilla
//And then to run:
filezilla
//https://github.com/chromebrew/chromebrew