You can easily scrape (or download) a site with a CLI tool called wget. It's available for Linux, Mac and Windows.
I recommend using Homebrew, especially if you're on a Mac, to install it.
brew install wget
wget -https://{SITENAME}.{TLD}
, example wget https://www.google.com
To scrape the main entry (mirrored) with 1 level recursion depth, with everything you might need to run the site locally:
wget -m https://{SITENAME}.{TLD} -r -l1 --no-parent --page-requisites --convert-links