The platform truck should have the option to have water like the type 1 and quint. Most platform trucks in the US have a water system to put out fires. If my closest unit is a platform for a car fire I shouldn’t have to dispatch another engine for a small car fire.
Another idea is to add heavy rescue equipment to type 1 engines. Fire engines irl usually have rescue equipment for car accidents and other emergency. For example, the animal stuck in wall mission needing two trucks for that is not very realistic, but if you add rescue equipment to type 1 you would only need 1 truck for the mission.
Last idea is to make K9’s equipment that you can buy instead of its own unit. You should have to buy a regular car but with an equipment tab like the fire station you can buy a K9. Irl K9 units can handle basically any police call because there is still an officer in the car. But to have a K9 the officer should still have to have training for it.
These are ideas that kinda change some missions but it’s realistic.