No, a function can be long but have a low cyclomatic complexity score [1] (being a list of do_this(), do_that(), do_somethingelse(), etc) while a short function can have a higher cyclomatic complexity score (lots of fiddly logic).
It might be reducing "cyclomatic complexity" but not necessarily overall complexity. Often the opposite is true: reduced locality imposes its own costs in maintenance and efficiency for example.