How do I use Join-Path to combine more than two strings into a file path?

Since PowerShell 6.0, Join-Path has a new parameter called -AdditionalChildPath and can combine multiple parts of a path out-of-the-box. Either by providing the extra parameter or by just supplying a list of elements.

Example from the documentation:

Join-Path a b c d e f g
a\b\c\d\e\f\g

So in PowerShell 6.0 and above your variant

$path = Join-Path C: "Program Files" "Microsoft Office"

works as expected!

You can use the .NET Path class:

[IO.Path]::Combine('C:\', 'Foo', 'Bar')

Since Join-Path can be piped a path value, you can pipe multiple Join-Path statements together:

Join-Path "C:" -ChildPath "Windows" | Join-Path -ChildPath "system32" | Join-Path -ChildPath "drivers"

It's not as terse as you would probably like it to be, but it's fully PowerShell and is relatively easy to read.