Is it possible to change the loadout of vehicles?

Yes, this is generally possible. However, this ability is only unlocked for special vehicles, as you can craft. You can find these in the Vehicle Crafting list with the name “Dynamic Loadout”. Alternatively, you can find all unlocked vehicles under the specification “Customizable” here: https://avmg.eu/index.php?faq-…d-deren-f%C3%A4higkeiten/

You can open the Pylon Manager at all hangars (also available for your own territory) via the scroll-down menu.