I need to install a beta version 3.0.0 of react-docgen.

Is it possible to install a beta version via npm?

The syntax for npm install includes both of the following overloads:

npm install [<@scope>/]<name>@<tag>
npm install [<@scope>/]<name>@<version>

For tag, you can specify either @latest and @beta like this:

npm install @11ty/eleventy@latest  # latest stable release
npm install @11ty/eleventy@beta    # latest beta release

Interestingly, if you don't specify a tag, the default, set by your npm config, is @latest

You can also find out which versions are available by running npm view

npm view @11ty/eleventy

npm view