git worktree add /path/to/empty/folder <branch_you_would_like_to_check_out>

A bit more detail

According to the docs (opens new window) - A git repository can support multiple working trees, allowing you to check out more than one branch at a time.

If you have two branches:

- feature_monday
- feature_sunday

And your repo is at

~/workspaces/my_monorepo

And you currently have feature_monday checked out - you can create a new folder called ~/worktree/ and inside of ~/workspaces/my_monorepo:

git worktree add ~/worktree/ feature_sunday

Git will clone the repo for you into the ~/worktree folder, and if you cd into the ~/worktree/ folder you will see that feature_sunday branch is checked out.