Install the pak to your paks folder with what you want! Currently the paks are Anakins head (Alpha) Anakins With Flaps (Alpha) and Anakin with skirt (Alpha).
(mine is C:\Program Files (x86)\Origin Games\Jedi Fallen Order\SwGame\Content\Paks) and you are good to go! In order to change styles in game, simply go to cal's customization tab and click on "outfit" and scroll through the selections! More outfits coming soon!