> In other systems I could say “<tool name> create branch x from parent y”.

While the default of `git branch` is to branch from the commit you have checked out, the command does take an optional argument for the start point of the new branch:

  git branch <new-branch> [<start-point>]

or, to create and check out in one go

  git switch -c <new-branch> [<start-point>]