How To Make a Static Copy of a WordPress Instance
WP2Static
This WordPress plugin should do the trick but when I tried it, the default page was not the same as intended and the link menu were all pointing to the homepage.
Maybe it was because of the permalink settings was not correctly configured, but I abandonned this idea.
wget
Back to basic, wget should do the trick!
wget -q --mirror --convert-links --html-extension --adjust-extension --page-requisites https://example.com/