Original Draco 3D Data Compression Unity Package
This package's original identifier was com.atteneder.draco
and was forked by Unity. Here's the instructions to use/install the original.
Via OpenUPM
The recommended way to install is to download and open the Installer Package
It runs a script that installs Draco 3D Data Compression Unity Package via the OpenUPM scoped registry.
Afterwards optional packages are listed in the Package Manager (under My Registries) and can be installed and updated from there.