https://typst.app/docs/tutorial/making-a-template/

Local packages

Want to install a package locally on your system without publishing it or experiment with it before publishing? You can store packages in {data-dir}/typst/packages/{namespace}/{name}/{version} to make them available locally on your system. Here, {data-dir} is

• $XDG_DATA_HOME or ~/.local/share on Linux
• ~/Library/Application Support on macOS
• %APPDATA% on Windows

Packages in the data directory have precedence over ones in the cache directory. While you can create arbitrary namespaces with folders, a good namespace for system-local packages is local:

• Store a package in ~/.local/share/typst/packages/local/mypkg/1.0.0
• Import from it with #import "@local/mypkg:1.0.0": *

Note that future iterations of Typst's package management may change/break this local setup.