When I want to test and learn a single package in Emacs it suits my best to create a simple empty emacs configuration directory in my src folder.
mkdir test-emacs-config
Then put in a very minimal .emacs file testing the package in question. The following sample tests the Vertico package.
;; -*- lexical-binding: t; -*-(require 'package);;; Start package configuration(add-to-list 'package-archives '("elpa" . "https://elpa.org/packages/") t)(package-initialize)(eval-when-compile (require 'use-package))(use-package vertico :ensure t :custom (vertico-cycle t) :init (vertico-mode) )
Now to test this config you have to start emacs with this file AND ignore the existing configuration that you have in your home dir.
emacs -q --init-directory=~/src/test-emacs-config -l ~/src/test-emacs-config/.emacs
The q parameter tells Emacs to ignore the standard config load. The --init-directory tells where to load finds from and the -l parameter tells which file to use as init.
You can put this into your aliases and make a simple command such as testemacs.
When starting emacs with this command it will execute the use-package command and download the vertico package into an elpa directory under the directory test-emacs-config.
By using this approach you can test out simple package configurations befor merging them into your main Emacs configuration.
Happy Emacs'ing :)